In order to improve cardiorespiratory and muscular fitness, bone health, reduce the risk of NCDs and depression:

1. Adults aged 18–64 should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous-intensity aerobic physical activity throughout the week or an equivalent combination of moderate- and vigorous-intensity activity.

2. Aerobic activity should be performed in bouts of at least 10 minutes duration. For additional health benefits, adults should increase their moderate-intensity aerobic physical activity to 300 minutes per week, or engage in 150 minutes of vigorous-intensity aerobic physical activity per week, or an equivalent combination of moderate- and vigorous-intensity activity.

3. Muscle-strengthening activities should be done involving major muscle groups on 2 or more days a week.

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Overall, strong evidence demonstrates that compared to less active adult men and women, individuals who are more active:

have lower rates of all-cause mortality, coronary heart disease, high blood pressure, stroke, type 2 diabetes, metabolic syndrome, colon and breast cancer, and depression; are likely to have less risk of a hip or vertebral fracture; exhibit a higher level of cardiorespiratory and muscular fitness; and are more likely to achieve weight maintenance, have a healthier body mass and composition.

People who got some exercise, but not enough to meet the physical activity recommendations were still 20 percent less likely to die over a 14-year period than those who did not do any physical activity. (The recommendations say to do 150 minutes of moderate activity per week or 75 minutes of vigorous activity per week.)

People who engaged in the recommended level of physical activity saw even more benefit: They were 31 percent less likely to die during the study period, compared with those who did not engage in any physical activity. [7 Common Exercise Errors and How to Fix Them]

But doing a lot more activity than that did not provide much added benefit. The maximum benefit was seen among people who engaged in three to five times the recommended levels of physical activity; they were 39 percent less likely to die over the study period than people who did no exercise. Engaging in more exercise than this was not linked with any additional benefit.

Who recommendation is 150 minutes moderate or 75 minutes vigorous a week. Three to five times this amount was linked with a 39% reduction in mortality; therefore, 7.5 hours moderate exercise or 3.75 hours vigorous for best results.