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.

BBC: Prolonged TV viewing linked to lower sperm count

If you have no time for the gym during the week, that's OK: Recent research shows moderate to vigorous exercise even just once a week (say, a weekend jog) makes you 30 percent more likely to maintain your cognitive function as you age.

CNN: Helpful ways to boost your memory