Optimal sexual health is also promoted by moderate, regular exercise. Again, the key is avoiding extremes. Studies show that men who exercise strenuously (i.e. men who run more than 100 miles a week or who bicycle more than 50 miles a week) usually have lower testosterone levels than men who exercise more moderately. Given that most men do not, in fact, exercise even moderately, this is not exactly a huge public health problem. Exercise at any level--even walking--is better than no exercise, but you derive maximum benefit when exercise is strenuous enough to be aerobic, meaning any activity that uses large muscle groups, can be maintained continuously, and is rhythmic in nature. Such activity causes the heart and lungs to work harder than normal, which is the key to both the physical and mental advantages of exercise.
When an overweight man, particularly one with excess abdominal fat, has low testosterone levels (which often the case), I do not recommend that he exercise right away. It's simply going to be frustrating because he will lack the drive and energy needed to initiate exercise. Instead, I wait for his testosterone levels to rise and, almost always, he finds he wants to exercise because it simply feels good. Exercise may cause an initial small weight gain from added muscle mass, but this is usually followed (in overweight men) by significant weight loss, because more calories will be being burned and the added muscle essentially raises a man's metabolism.
Men need to think about their sexual health when they're making choices about which foods to eat and whether or not to exercise. It's one thing for a man to know in the abstract that it's good to exercise and eat right--it's quite another to understand that doing so will help his sex life and potency.
Used with permission from The Male Biological Clock.