Don't stress out over it.

I'm Patrick, John's brother.

I too constantly feel that I should be more successful, and I'm pretty sure the feeling doesn't go away -- no matter what's achieved.

I think looking at others can be a useful gut check: am I working as hard as I could? Am I as focused as I'd like to be? But given that there's so much randomness and circumstance there too, it's a bad benchmark for anything.

(For what it's worth, the check I use personally is: "is there a difference between how those who know me best would describe me, and how I'd like to be?" Most of the time, I just try to fix those gaps.)

Good luck!