Try Rock Climbing. You get all the benefits of the gym (it works pretty much everything), plus all the leveling up benefits from WoW.
Every sport climb and boulder problem is graded. Most of them you won't be able to do. You'll need to spend weeks at first to get good enough to even do the easy ones. The hard ones will take years to get strong enough for, and even then will still require you dedicate a month of specific training for that one single route.
Leveling up? It's got that too. Climb at the gym for a while and soon you'll get to the point where you've done your first V1 problem. V2 is an order of magnitude harder, as is V3. The scale goes to V16 (at the moment), and 15 years of motivation have thus far only gotten me as far as V8. Given the dedication of a recovering WoW addict, I think climbing would fit your psyche perfectly.
Oh, and it's crazy fun too, so no more of this "I should go to the gym" crap. You'll go. You'll be upset if work intrudes on your climbing time. You'll start taking climbing trips instead of vacations, and eventually forget when it was that you last boarded a flight without your rock shoes.
You'll start spending your winters climbing rocks at Tonsai beach [1] in Thailand. I'll buy you a beer when you get there.
[1] http://blogabond.com/Photos/PhotoView.aspx?imageID=2746