"By preparing your body ahead of time, you're getting it in the best possible shape for the marathon of pregnancy," says Dr. Mazzullo.

Although exercise, per se, doesn't affect a man's fertility, what he wears during exercise can. Men who spend time a lot of time in a jock strap, for example, should limit wearing one as much as possible during the conception period because it can heat the testicles and lower sperm count. For the same reason, men also should limit their time in a hot tub, spa or steam room to 15 minutes twice a week.

Source: http://resources.purematters.com/healthy-body/pregnancy/4-tips-for-couples-trying-to-conceive