I suggest regular exercise as a part of any entrepreneur's daily routine, not so much for the physical benefit, but for the mental benefit.  I recently lost 50 pounds and I have to say it's the best thing for me physically AND professionally.  It builds up dedication, gives you time to think, and makes you see that hard work pays off.  You won't lose a pound the first day, or sometimes even the first week.  Once you do see things paying off, it usually motivates you a lot more.  Applying these same principles to starting a company is one hell of a motivator.