By far the best workout I've ever done to prepare for a season of shredding (not to mention general strength and health.) It combines compound movements (i.e. olympic lifts, pull-ups, etc.) with short, intense bursts of cardio for a complete, full-body workout. Workouts rarely take longer than 20 minutes, but you will be wasted after almost all of them.
Some examples of Crossfit workouts:
5 rounds for time of:
400 meter run
95 pound Overhead squat, 15 reps
Ten rounds for time of:
3 Weighted Pull-ups, 45 pounds
5 Strict Pull-ups
7 Kipping Pull-up
Four rounds for time of:
Run 400 meters
As many rounds as possible in twenty minutes of:
Most cities have dedicated Crossfit gyms with trainers certified to teach the movements and theories of Crossfit. This is not cushy personal training at Gold's Gym. It is the sport of fitness.