There is a safe way to develop a personal fitness program.
First, check with a physician who will measure your physical capacities and limitations. Depending on your age and other factors, he may recommend an exercise stress-test including an electrocardiogram taken while exercising. This will allow him to Judge your present physical condition and the amount of exertion you can safely handle.
Second, select an appropriate exercise program. Divide it into training sessions of three phases; 5-8 minutes of warm up; 20-25 minutes of work-out; and a 5-8 minute recovery period.
The exercise work-out phase should involve the large muscle groups such as those of the back and legs. Activities like cycling, swimming, walking. Jogging, or a combination of these will produce best results.
Interval-type activities that produce episodes of increased heart rate followed by rest appear the most effective to develop and maintain fitness.
To change from a state of being unfit to one of being fit requires at least four, and preferably five, exercise sessions a week. Once increased fitness has been attained, three intensive sessions will maintain your fitness.
Don't worry about fatness; work on developing fitness. If you want to trim your figure, adjust your food intake to lessen your energy output by at least 500 calories per day. In a week, this energy deficit will result in one pound of weight loss.
Stick to it and make fitness a part of your life pattern. There is supportive evidence to indicate that exercise and fitness are reasons that "primitive" people are immune to the chronic diseases of late life so prevalent among developed but sedentary societies.
Along with some soreness and swelling, minor complications such as foot, ankle, or knee discomfort may occur as a result of increased exercise activity. If any of these complications should occur, physical fitness experts recommend that you modify activity by reducing the intensity and/or duration of exercise. If the problems should persist, see your physician.