This is my most important lesson in the past few years. There is value in _not_ learning, building, doing all the time.

I like to work and study, but doing either of it for more than 8hrs is not sustainable for me. I expect to be writing the modern-day equivalent of Fortran when I'm 60. All the young bucks will look down on me for not advancing in my career, but I think I'll be happy. That's all I need.

Everyone has their own balance point. John Carmack can work 12hr days and improve at various subjects continually, so his balance point lies somewhere else. Don't try to be Carmack if you're not and you can still live a fulfilling life :).