I'm starting to adopt more running into my weekly duties. Whereas it was cyling 6 days a week, it's now running 2 or 3 days a week on top of riding the other days, with varying distances of 3-5 or 6 miles. I'm a 5 small meals a day eater, and generally on my way home from work, I'll have an apple and some water because I go right out and either ride or run when I get home. I've noticed that lately, I've gotten stomach aches. I'm well aware that this isn't something out of the ordinary, but what causes it? And how can I stop it? My legs have more miles in them but my stomach doesn't and it's bumming me out.