The answer is going to sleep, at a regular time. Put down the computer, put down the cell phone, put down the games. Go to bed early. Above all else I make sure

The answer is going to sleep, at a regular time. Put down the computer, put down the cell phone, put down the games. Go to bed early. Above all else I make sure I get my eight hours every night. If I'm tossing and turning, I'll call into work. As a result, I am NEVER sick. Ever. Anecdotal sure, but if I don't get sleep, I feel like I'm coming down with something. Also naps, take advantage of them. I'll often go home on lunch, and take a snooze for an hour.