I've done 85-90 a week for 5-6 years and don't get burned out through strict discipline. I'm perfectly healthy and spend at least 15 hours a week with loved ones and get at least 6-7 hours a night sleep.

10am - Wake up, no flexibility here. Get up.
1030-6pm - Work
6 - 9pm: 20min nap, 20min run, 20min cooking, 2 hours with loved ones.
9pm - 3am - Work.

6 days a week, and Sunday is a wild card. I'll sometimes sleep in and just do the night shift on Sundays.

• Three coffees per day on a strict schedule and don't go over or you'll break your schedule.
• Lots of water.
• Bi-phasic sleep schedule 6h + 25m nap
• Don't miss exercise or you'll loose energy and focus.
• Heavy breakfast (eggs) + pre-cooking lunch day before will keep you healthy so don't eat junk food when tired.