Not putting down Crossfit, but you don't have to join it to get buffed out. Overworking yourself won't get you there.
Do fairly strict Primal eating.
Get plenty of rest. That's when your muscles recover and grow.
Vary your resistance work based on Mark's guides.
Oh, and get a genetically gifted body. That's the hardest part. I don't mean to be flippant. You may not turn out just like Mark. But you will be in great shape.