Comment by Trasmatta

I think Carmack has been able to consistently work these extended hours his entire career because he's always had the chance to work on really interesting problems that excite him. I can also work long hours for extended periods of time when that's the case. The burnout for me comes in when the work feels pointless, and I have no autonomy. That's when I can barely even put 8 hours in without my entire body and mind shutting down.