I've always been a competitive athlete so I guess my opinion doesn't count, but...
After blowing up to nearly 390 LBS I-CAN'T-WAIT (!) until I'm down to a weight that allows me to be competitive again.
40 LBS later and I'm already feeling that itch.
The endorphins are fabulous, but the satisfied exhaustion I feel after busting my ass is what really makes it worth it. In my experience, you'll never truly appreciate how nice it is to relax on a couch until you've first come to appreciate hard physical work.
I began this Primal journey on December 30th, 2009 and in that time I've lost over 125 LBS.