This is a cool site -- great start! I would like to make a couple of suggestions:

1. don't just focus on exercise, include an "eat healthy" component too (maybe based on both calories and general healthy food attributes)

2. Find a way for user goals. Maybe a "self directed quest" is required for any given level, be it lose X pounds, or reach Y bench weight.

3. Find a way to keep stats for people and show them graphs of improvement (or otherwise), not just levels, but attributes :)

Keep up the good work.