Don’t boil your testicles by wearing super-tight underwear no matter how sexy, and get up from behind that computer and walk around once in a while to get some circulation going down there.  Have you ever been to a Japanese or Korean spa where they have cold baths and ice saunas?  In Russia there is a tradition of bathing with buckets of ice cold water, and this is great for your nervous system as well as your sperm production.