P90X
Spent probably 10 years doing P90X workouts. I've done several other workout programs and nothing comes close to the excellence of P90X.
Upper body, lower body, abs, yoga for stretching and balance, martial arts for aerobic and balance - it is a complete package.
When I first came across it I showed it to my wife. God bless her, because her immediate response was "You can't do that!" - and I swore at that very moment that I would die trying before letting her be right. Sometimes a stubborn streak can be a good thing!
Those first weeks I about died. I'd finish a workout and lie down, curled up on the floor, praying for recovery. Very sore, very tired, yet still I was faithful to the workouts along with the diet. They give you specific calorie counts and recipes for meals, but it's mainly focusing on proteins and avoiding carbs. Stuck with it and finished the 3 month program, then went back and started repeating the workouts over and over.
Like I said, it's my favorite.