How can i lose some of the muscle i gained playing sports and still stay healthy?

Train Your Muscles: Muscle loss is generally discouraged, but if you feel you've bulked up too much, it's possible to redirect your muscle mass to more lean muscle. If you weight train, focus on lighter weights w/ higher repetitions. Increased aerobic activity (e.g., swimming), can also promote more lean muscle mass. The key is to re-train your muscle, not lose it. Eat and hydrate well, and keep exercising!

Cardio: More cardio and less resistance exercises (weight lifting).