BJJ in a nutshell.

1)Learn to absorb punishment (White belt)
2)Learn to escape from basic positions consistently (White Belt)
3)Learn techniques & submissions, sweeps/reversals (Blue Belt)
4)Play guard and pass guard (Blue Belt)
5)Develop positional control (Purple Belt)
6)Develop transitions and flow (Purple belt)
7)Develop a Solid Game (Brown Belt)
8) Look for a weakness in your skill set (Any level)
9) Repeat, return to Step 1.

I think thats why so few people who start BJJ continue for the long term because steps 1 & 2 are so hard. But thats also the beauty of the art in that this learning process is endless and evolving. The other thing I like is that whenever you roll with someone much better than you, you can go back to step one all the time regardless of the belt colour around your waist