Do you want to get into shape or get back in shape? Speaking from an athlete's view, staying in shape while participating in athletics can be a drag. But it keeps you healthy and fit. From my days of being a swimmer, I recall lifting weights three times a week. We worked on our midsection areas, while attacking the leg and arm muscles. I was in the best shape of my life. Now that I'm no longer an athlete, I am not as active as I once was. But I try every week to stay in good shape. I recommend doing these lifts.
For arm workouts, our swimmers did bench press, push-ups, lat pull down, occasional pull-ups, bicep curls, tricep extensions, and more. We did 3 sets of 12 reps for each station. But when lifting weights, you will want a spotter or partner with you, making sure you're doing the lift correctly and that you are safe. During each swim season, I had huge arms that helped with my pulling for each stroke I took.
For leg workouts, we did squats, leg curls, sprinting and suicides, box jumps, lunges, and leg extension. We also did 3 sets of 12 reps for each station. I recommend doing arm day for Monday, legs for Wednesday, and both for Fridays. At first, your legs will burn so much, it'll be hard to sit down, but in the end, it will be worth it. Doing these each week, you will have a fit body, if not toned.
Also, we did ab workouts before starting the weightlifting. We did crunches, flutter kicks ( legs straight out, kicking up and down), bicycles, and berry pickers. If these don't work, I recommend doing reverse crunches. Reverse crunches usually do the trick, if the regular crunches do not work. Doing ab workouts will tone your midsection and abs. While doing all these, you will also have an appetite, which I call the swimmer's appetite.
When going off to college, there are more opportunities that will probably distract you from working out completely. If you can, make time to work out. Working out will decrease stress and increase your appetite, while helping your body get toned. Doing these exercises every other day will get you the body you want.