The CDC and the AHA recommend that adults spend a minimum of 30 minutes a day, five days a week, doing moderate-intensity exercise, or at least 20 minutes a day, 3 days a week engaged in vigorous activity.
Men who were the most physically active, doing 15 hours or more of moderate to vigorous exercise each week by playing football, baseball or basketball for example, had sperm counts which were 73% higher than those who were least physically active.