Eat  meat and vegetables, nuts and seeds, some fruit, little starch and no  sugar.  Keep intake to levels that will support exercise but not body  fat.  Practice and train major lifts: Deadlift, clean, squat, presses,  clean & jerk, and snatch.  Similarly, master the basics of  gymnastics: Pull-ups, dips, rope climb, push-ups, situps, presses to  handstand, pirouettes, flips, splits, and holds.  bike, run, swim, row,  etc, hard and fast.  Five or six days a week.  Mix these elements in as  many combinations and patterns as creativity will allow.  Routine is the  enemy.  Keep workouts short and intense.  Regularly learn and play new  sports.