You know you should exercise more, and you’re ready to do it, but you have a few questions. The problem is the answers seem so complicated, especially since you’re not looking to achieve elite performance, just good health.

The following are straightforward answers to fundamental questions about exercising for health, so you can stop wondering and start exercising with confidence.

How much exercise do I need to benefit my health?

With rare exception, any increase in the amount of exercise you’re doing will benefit your health. This is important to realize because it means that every effort you can make will be worthwhile.

To get substantial benefits, the Department of Health and Human Services (HHS)1 guidelines specify that adults should get 150 minutes of moderate intensity, or 75 minutes of vigorous intensity, physical activity weekly. Of course, more exercise will yield additional benefits, but whatever you can do is still better than zero.

School-age children and youth should be more active than adults and get at least 60 minutes of moderate-to-vigorous activity daily from a variety of activity types.

How often should I exercise?

Exercise is cumulative, so spread it out through the day or over a week in any way that works for you. The HHS guidelines are based on 30 minutes a day, five days a week, although exercising everyday can make it easier to build and keep the habit. However, if you are exercising every day, then vary your exercise type and intensity so your muscles have time to recover in between. And if you can’t find larger blocks of time, especially when you’re just starting, then 5- to 10-minute bursts of increased activity still add up.

Is there a best time of day to exercise? 

For health, it’s more important that you do exercise than when you exercise. Because high-intensity exercise disrupts sleep for some people, it can be helpful to separate vigorous exercise from bedtime by an hour or more, but the simple answer is exercise whenever you can.

What kind of exercise should I do?

The simple answer is any kind of exercise you will do. HHS guidelines recommend aerobic exercise (brisk walking, swimming, biking, rowing) three days a week and strength training (e.g., weights, pushups, pullups, planks) two days a week.

But those don’t have to be separate activities – the goal is to challenge your cardiovascular and musculoskeletal systems several times during the week, so pick exercises that get your heart going and challenge your muscles. If you’re sore after exercising, then do a different exercise for a day or two before engaging in the earlier exercise again.

Keep in mind that regular activities also count as exercise if they have enough intensity. Look for opportunities in your daily life and be creative – do squats instead of bending, do isometrics (tensing muscles without moving) while you’re waiting, or wash the car as fast as you can. 

How hard should I exercise? 

According to HHS guidelines, “Adults who sit less and do any amount of moderate-to-vigorous physical activity gain some health benefits.”1 What constitutes “moderate-to-vigorous physical activity”? One way to gauge intensity is to pay attention to how hard you are working.

Moderate activity feels like you’re working about half as hard as you are capable. During moderate activity you breathe a little harder and your heart rate is faster than usual but not pounding, and you begin to sweat if you keep it up long enough. You can still talk, but you might not be able to sing. 

With vigorous activity you’re working hard but not at your max. During vigorous activity, your breathing is fast and deep, your heart rate is high but not pounding, and you’re sweating. It’s difficult to have a conversation without pausing, but you can still catch your breath.

A more objective measure is to use your heart rate as a gauge. It isn’t necessary to check your pulse during exercise unless you’re concerned that your heart is working too hard, but doing so provides useful data. Start with finding some basic heart rate values. 

1. Resting Heart Rate – This number gives you an idea of your current fitness.  It’s likely to go lower as you exercise more.

To calculate: Take your pulse when you are calm.

Example person:  72 beats per minute (bpm)

2. Maximum Heart Rate – This is an estimate of the fastest your heart should beat at any time.  

IMPORTANT: When your heart rate is near or over this number, you’re working too hard and it could be dangerous. Reduce your exertion to get your heart rate back into a safe range. 

To calculate: Estimate this number by subtracting your age from 220. 

Example person:  For a 34-year-old, 220 minus 34 = 186 bpm

3. Heart Rate Reserve – This is the difference between your resting heart rate and your maximum heart rate; it represents the range your heart can operate in. 

To calculate:  Maximum Heart Rate minus Resting Heart Rate = Heart Rate Reserve 

Example person:  186 minus 72 = 114 bpm

Use these numbers to calculate your target heart rates for exercising. 

4. Minimum Moderate Target – This is the lowest heart rate you should target during moderate-intensity exercise. Although you obtain health benefits from any extra activity, keeping your heart rate above this number during exercise yields more benefits, faster.  

To calculate:      Resting Heart Rate plus 50% Heart Rate Reserve = Minimum Moderate Target 

Example person:  50% Heart Rate Reserve = 114 x 0.50 = 57 bpm 

72 + 57 = 129 bpm

5. Minimum Vigorous Target – This is the lowest heart rate you should target during vigorous intensity activity. Keeping your heart rate above this number during exercise yields benefits faster than when your heart rate is lower.

To calculate:      Resting Heart Rate + 70% Heart Rate Reserve = Minimum Vigorous Target 

Example person:  70% Heart Rate Reserve = 114 x 0.70 = 79.8 bpm 

72 + 79.8 = 151.8 bpm (round to 152) 

6. Target Heart Rate Limit – Keep your heart rate below this number. Although your heart can beat faster, there is no additional benefit and it could be dangerous. 

To calculate:      Resting Heart Rate + 85% Heart Rate Reserve = Target Heart Rate Limit

Example person:  85% Heart Rate Reserve = 114 x 0.85 = 96.9 bpm

72 + 96.9 = 168.9 bpm (round to 169)

It isn’t necessary to recalculate these numbers as your fitness changes because they won’t change by much.  

Use your target heart rates to assess your intensity level during exercise. Don’t worry about being too precise.

1. Measure your pulse while you are exercising. 

Example person:  Count 73 pulses in 30 seconds and multiply by 2 to get 146 bpm. 

2. Compare your exercising heart rate to your target heart rate values. 

Example person:  146 is above 129 and below 152. This is moderate intensity for the example person.

3. Adjust your exertion level as needed. 

Example person:  No change for a moderate goal but increase pace or effort to achieve a vigorous goal.

4. Recheck your heart rate periodically while you exercise. As you get more familiar with how your heart rate is affected by exercise you can check less often.

What else do I need to know before I start? 

It’s always a good idea to discuss your exercise plans with your health-care practitioner before starting a new routine. This is especially important if you have a pre-existing condition or concern that is relevant to exercising, or if you are pregnant.

Keep in mind that exercise intensity is relative to your fitness level, so what was hard last month might be easier next week, and what is moderate for one person might be vigorous for someone else. Avoid comparing yourself to others. Do what you can. Pay attention to your body and adjust as needed – discomfort is good, pain is bad. Start slowly and work your way into larger amounts of more vigorous activity over time, especially if you haven’t been active lately. 

For more information and tips on getting started and sticking with exercise, check out Making Exercise a Reality – 10 Tips for Success.


1. U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition. Published online 2018. [Accessed April 30, 2020].