Based on my time as an active duty squid (6 years), my experiences in boot camp, various schools ("A," "C," etc., etc.), and my knowledge of the reservists (there are non-prior service programs for people who have critical skills, meaning no real boot camp required), it should be fairly rinky dink. As long as you're not grossly obese, I wouldn't get too worried about things. However, if your body fat percentage is borderline, you may want to start working out a little and cutting back on your meal portions. Otherwise, you could spend some of your liberty time in Pensacola doing remedial PRT, vice hitting the beach.