Time? I heard somewhere that if you work for yourself that you could have enough.  LOL. I wake up with keyboard impressions in my forehead... I think it's becoming a permanent feature.
  Seriously, though, one thing that helps me, is to take some time out, and decompress... make a sandwich... just fiddle with something for a bit... that kind of thing.
  Excercise? Well, I'm teaching my daughter....... don't tell her I told you, but she's in her 30's... Swordsmanship, using full-sized Scottish Claymores..... let me tell you... swinging twelve pounds of steel for two hours a day gets..... interesting... especially since she's getting much faster.
  I think, though, that, you have to have fun with what you're doing. If you can fall, exhausted, into bed, feeling that you accomplished something..... isn't that worth it? Lou.

P.S. Yes, I wake up in the morning, grumbling about not enough sleep.... quoting from a Miyazaki movie... "More sleep, please".

"..... and that was when things got interestiing."