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How to be Fit? – What Exercises to Do to be Fit at My Age?

The formula and the frequency of exercises to do to be fit for each age group

Why does your weight matter? What do people mean when they say they want to be fit?

Here it means to keep your body fit and avoiding all the health risks that we are prone to with a gradual increase in age.

To be fit is or keeping a suitable weight and body fat mass can spare you from some diseases and suffering and also increase your life span.

But there is always betterment in moderation.

  • Having too low body fat and nutrient deficiencies from low food intake can make you lethargic and also lead to increased risk of fractures, illness, loss of reproductive function, and early aging.
  • Having too much body fat (above 25% for women and above 20% for men) renders a greater risk for developing life-threatening non-communicable diseases (NCDs). (Click to find out if what is an ideal body fat ratio for you)

The formula to manage your weight to be fit

Energy Intake – Energy Expenditure = -3,500 kcal = 1 lbs of body weight loss

If you cut 500 calories from the usual diet each day, you’d lose about 1 pound a week.

Weight loss is a cumulative energy deficit of 3,500 kcal per pound of bodyweight loss or 32.2 MJ per kg – only through adjusting the volume of physical activities (energy expenditure) and the intake of food (energy intake), we lose, maintain or gain weight.

Here; 1lbs. equal to 3,500 kcal.

In a study that evaluated the effectiveness of weight loss by methods, weight loss, lowering body fat mass, is best achieved by a combination of diet and exercise (+276%) then diet alone (+170%), comparing to the only exercise.  The test involved a 500-1000 kcal/day deficit per day and 45 minutes of moderate-intensity physical activity for 5 days a week.

In another study was carried out for calculating optimum weight loss via diet and with or without exercise. This resulted as more weight loss and aerobic stability were achieved by women who followed diet and exercise. Maximum exercise potential was also better in women who were physically active. However, there are some studies that show that exercise has no significant effect on weight loss.

Click if you’d rather find out now whether you reach the definition of being fit and if you choose your food properly to optimize your health.

What are the benefits of exercises or physical activities?

To be fit or active is associated with a greater than 50% reduction in health-related risk.

All-cause mortality

Cancer-related death
Middle-aged women
Physically Inactive (<1 hr of exercise/week) vs
Physically Active (>1 hr of exercise/week)


An increase in energy expenditure from the physical activity of 1,000 kcal per week or an increase in physical activity of 1 MET (metabolic equivalent) was associated with a mortality benefit of about +20%.

The best time to start being physically active is – Now.”

An increase in physical fitness will reduce the risk of premature death, and a decrease in physical fitness will increase the risk.  Even small improvements in physical fitness are associated with a significant reduction in risk.  People who went from unfit to fit over a 5-year period had a reduction of 44% in the relative risk of death compared with people who remained unfit.

How much exercise to do per week for each age to be fit?

The volume of exercises, at every stage in life, renders a tremendous effect on your health.

The recommended minimum physical activity of 150 minutes of moderate to vigorous aerobic physical activity per week is associated with a 20-30% lower risk of chronic diseases and premature mortality.

The greater the amount of physical activity, the greater the health benefits.

Health-related Risk[i] in relation to
physical activity

All-cause mortality

Cancer-related death

Adults with 15 minutes of physical activity per day
Vs inactive adults


+3 years of life expectancy


Additional 15 minutes

-4% -1%
150 minutes per week -20%~30%


As we age, the development of our bodies can be enhanced by adjusting the duration and intensity of physical activities.  Below are the recommendations and benefits highlighted by the World Health Organization:

[i] The health benefits of physical activity and cardiorespiratory fitness,

Children and young people aged 5-17

The peak physical fitness and performance of the human body is in the early 20s.  This phase is important to develop the growth of musculoskeletal tissues and important internal organs serving as a stronger foundation for better health in the future.

Recommended levels of regular physical activity for 5-17:

  • 60 minutes of moderate to vigorous-intensity daily (420 minutes per week)
  • Physical activity incorporating aerobic activity 
  • Muscle and bone-strengthening activities involving major muscle groups on 3 times per week
    • Playing on playground equipment
    • Climbing trees
    • Playing tug-of-war

Benefits of exercises for children and young people

  • Maintenance of healthy body weight.
  • Healthy musculoskeletal tissues such as bones, muscles, and joints.
  • Healthy cardiovascular system – note that coronary artery disease begins in childhood
  • Neuromuscular awareness including coordination and movement control
  • Psychological benefits (improving control over symptoms of anxiety and depression).
  • Social development (self-expression, building self-confidence, social interaction, and integration).

Adults aged 18-64

Even the peak of our physical fitness is declining from the 20s, our body is still strong and can be strengthened to avoid diseases and to support good health in the long run.

Recommended levels of weekly physical activity for 18-64:

  • 150 minutes of moderate-intensity or at least 75 minutes of vigorous intensity per week
    • 300 minutes of moderate-intensity or at least 150 minutes of vigorous-intensity yields additional health benefits
    • Brisk walking
  • Muscle-strengthening activities involving major muscle groups 2 or more times/week.
    • Calisthenics that use body weight for resistance (such as push-ups, pull-ups, and sit-ups)
    • Carrying heavy loads
    • Heavy gardening (such as digging or ploughing)
  • Aerobic activity should be performed in bouts of at least 10 minutes duration
  • Flexibility training on major muscle and tendon groups such as yoga for at least 10 minutes and 2-3 times a week

Benefits of exercises for adults aged 18-64

  • Lower rates of all-cause mortality, coronary heart disease, high blood pressure, stroke, type 2 diabetes, metabolic syndrome, colon and breast cancer, and depression.
  • Lesser risk of a hip or vertebral fracture,
  • Higher level of cardiorespiratory and muscular fitness.
  • Weight maintenance, a healthier body mass and composition
  • Better mental health .

Adults aged 65 years and above

At this stage in life, the main focus is to improve cardiorespiratory and muscular fitness, bone and functional health, reducing the risk of noncommunicable diseases (stroke, diabetes, heart disease, cancer), falls/bone fractures, depression, and cognitive decline.

Recommended levels of weekly physical activity for 65 and above:

  • 150 minutes of moderate-intensity or at least 75 minutes of vigorous-intensity/week.
    • Exercising more that this yeilds additional benefits.
  • Muscle-strengthening activities involving major muscle groups 2 or more times/week.
    • Digging, lifting, and carrying as part of gardening
    • Mild activities of sports
    • Household chores
    • Carrying groceries
    • Some yoga and tai chi exercises
    • Strength exercises are done as part of a rehab program or physical therapy
  • Aerobic activity should be performed in bouts of at least 10 minutes duration
  • Older adults, with poor mobility, should perform physical activity to enhance balance and prevent falls on 3 or more days. (standing on one foot with support)
    • Flexibility training such as yoga for at least 10 minutes and 2 times a week.
    • If they are not able to perform recommended activities due to underlying health causes, they should be as physically active as much their condition allows.

Benefits of exercises for adults aged 65 years and above

  • Lower risks of fall/ Better balance,
  • Lower rates of coronary heart disease, hypertension, stroke, diabetes, colon and breast cancer,
  • Higher level of cardiorespiratory and muscular fitness,
  • Healthier body mass and composition and enhanced bone health,
  • Better cognitive function.

What are the Moderate-Intensity and Vigorous-Intensity physical activities?

According to the World Health Organisation, the intensity of physical activity is different from one person to another as it depends on each individual’s previous exercise experience and relative level of fitness.

Measurement of the intensity using Metabolic equivalents (METs)

The intensity of exercise can be expressed through MET – the ratio of a person’s working metabolic rate relative to his/her resting metabolic rate (World Health Organization).

1 MET is defined as the energy it takes to sit quietly.  For an average adult, it is about
1 kcal / 2.2 lbs or 1 kg / hour
If you weigh 160 lbs, 1 MET is ~72 kcal per hour.

Moderate-intensity activities (3-5.9 METs) would mean activities that would require 3-5.9 times the energy to 1 MET (sitting quietly).  For example, for an adult weighing 160 lbs; the moderate-intensity exercise would be one that requires the energy of a minimum of 216 kcal (3 times x 1 MET of 72 kcal).

Measurement of the intensity using maximum heart rate (MHR)

Alternatively, heart rate relative to the maximum heart rate of an individual when performing the exercise can be used as an indicator of the activity’s intensity.  With the widespread of heart rate monitors, this is an easy way of measurement.

American College of Sports Medicine (ACSM) recommends this formula as a rough baseline:

220 – Age = maximum heart rate (MHR)
If you are 40 years old, your MHR is 180.

A general guide for moderate and high-intensity activities for reference

Physical activity MET
Light intensity activities – <50% of MHR

For example, <90 beats per minute for a 40-year old adult

< = 2.9
sleeping 0.9
watching television 1
writing, desk work, typing 1.5
walking, 1.7 mph (2.7 km/h), level ground, strolling, very slow 2.3
walking, 2.5 mph (4 km/h) 2.9
Moderate intensity activities – 50-70% of MHR

For example, 91 – 126 beats per minute for a 40-year old adult

3 to 5.9
bicycling, stationary, 50 watts, very light effort 3
walking 3.0 mph (4.8 km/h) 3.3
calisthenics, home exercise, light or moderate effort, general 3.5
walking 3.4 mph (5.5 km/h) 3.6
bicycling, <10 mph (16 km/h), leisure, to work or for pleasure 4
bicycling, stationary, 100 watts, light effort 5.5
sexual activity 5.8
Vigorous-intensity activities – 70-85% of MHR

For example, 127 – 153 beats per minute for a 40-year old adult

>= 6
jogging, general 7
calisthenics (e.g. pushups, situps, pullups, jumping jacks), heavy, vigorous effort 8
running jogging, in place 8
rope jumping 10

A table that lists out the MET value per common daily physical activity and the % to maximum heart rate on activity intensity

Does physical activity improve my existing disease?

Energy expenditure of about 1,600 kcal (6720 kJ) per week has been found to be effective in halting the progression of coronary artery disease, and energy expenditure of about 2,200 kcal (9240 kJ) per week has been shown to be associated with plaque reduction in patients with heart disease.

It has been proven in a study that physical activity when started at early ages reduces of all-causes mortality.

  • Reduced risk of cancer (all types)
  • Reduced risk of dementia
  • Reduced risk of excessive weight gain in children, adults, and pregnant women
  • Reduced risk of gestational diabetes and postpartum depression
  • Reduced risk of fall-related injuries in older people.

In addition, there is evidence that physical activity is associated with

(1) improved Quality of life, improved sleep, reduced feelings of anxiety and depression in healthy people and in people with existing clinical syndromes, and improved cognitive function across the life span.

Low-intensity exercise training (e.g., exercise at less than 45% of maximum heart rate) has also been associated with an improvement in health status among patients with cardiovascular disease.

The Bottom Line

We can only reap the benefits of being physically active through a consistent and long-term practice integrating a regimen of regular physical activities into the lifestyle.

The change of lifestyle can be a bit daunting so it is important to continuously keep yourself motivated.  Here are some tips to keep the motivation going:

  • List out the motivations for being physically fit.
    • Whether it’s about looking better, feeling better, improving mood, or avoiding diseases
    • Find out what you want from these lifestyle changes.
  • Identify your improvements.
  • Use an activity tracker. There are many activity tracker and gadets available online that can keep you motivated. They track sleep, steps, heart rate, BP etc.
  • Variety is the key. Keep on changing your workout regime from slower to faster pace.
  • Find a workout buddy or a group of fitness family and friends.
  • Conduct a thorough medical examination after at least 3 months
  • Observe your progress through heart rate monitoring between the medical examinations

Click to find out what exercises to choose from and how fit or unfit you are.

Check out The Zero-Minute Workout (Ep. 383) by Freakonomics that also shares the benefits of exercises by Michael Joyner physician-scientist at the Mayo Clinic and the latest research on a pill that requires zero-minute exercise as well as experts’ opinions on the pill.

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Lois Chan

Lois has worked in the health and skincare industry since 2004. Highly optimistic about aging, she is still pragmatic enough to prepare thoroughly for the future. is Lois' brainchild; a website offering scientifically researched solutions to challenges that people face in every stage of their lives. Join her on her journey for wisdom through the ages.

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