How to tell my football coach I want to quit?

I'm 16, 140lbs, 6'1, going to be a junior, and I'm a good cross country runner and a "okay" football player. In my school's athletic program, football is top priority, and practices are 3 hours everyday. This leaves little time to practice cross country (my favorite sport). Last year I went to one or two practices, and got 14th in our varsity cross country district meet, which is good considering we have the hardest cc district in the state. My cc coach tells me I have a really good chance at making regional and possibly state if I practiced. This sounds a lot better than being on the JV football team for the third year in a row, along with maybe 2 or 3 other juniors. So I have decided to quit football, but I don't know how to tell my coach. He's one of those coaches that preaches to you about dedication and commitment everyday, and doesn't like somebody that gives up. So how can I tell him that I want to quit so that he understands?