With too much weight, there can be hormonal disturbances, and when a man's too lean, he can have decreased sperm count and functionality. Exercise in moderation. Excessive exercise could lower your sperm count indirectly by lowering the amount of testosterone in your body. Value your vitamins. Low levels of vitamin C and zinc can cause sperm to clump together, so keep your numbers up.
Vitamin E can counteract excess free-oxygen radicals, which can also affect sperm quality.
Turn your back on toxins. So if a guy wants to be really fertile, boxers are the way to go. Truth is, this has yet to be scientifically proven. But if you're trying to get pregnant, there's no harm in wearing loose clothing and staying out of hot tubs and saunas. Since infertility affects one in 25 men these days, maintaining a healthy lifestyle and a positive attitude is the way to go if you're considering becoming a father.