loose skin weight loss

Goals: I want to gain strength and muscle mass while at the same time keeping my body fat in check. 20% (Possibly 18%, it was taken with calipers and I have a lot of loose skin from previous weight loss) is a little high and if I can lower it while simultaneously building muscle that would be great. For this reason I'm going to be doing light cardio 2-3 days a week for 10-20 minutes at a time. I'll be joining the Air Force in the summer and I want to use all the time before that to gain as much strength/muscle as I can while keeping below the weight limit (197) to enlist. After I get out of basic training and into a routine I'll jump right back into it.