Keep workouts short, intense, and varied.
Practice and train functional, compound movements: Squats, deadlifts, presses, cleans, and snatches.
Master the body weight movements: pull ups, push ups, hand stands, sit ups, throws, holds, and rope climbs.
Run, jump, bike, swim, row and climb, hard and fast.
Combine these exercises in as many combinations as creativity allows. Routine is the enemy; keep your body guessing. In other words, constantly varied, functional movement done with high intensity.
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.
(adapted from CrossFit Inc.)
And remember: Physical training is of some value but spiritual training has value for all things.