Military before college football?

I'm a football player at a 1A high school. We didn't do very good last year and I have one year left. I'm not big and would like to play a different postion but our coach won't let me. Tells me I'm the most experienced at that postion. I have a friend that graduated like 3 years ago, but didn't go to college ball because he wanted a D1 not a D2. So he joined the Marines to get bigger. Is this posible that you join the military to get bigger and then play college ball? if so can you name some player in the NFL that did this?