Ask HN: How do you keep your energy at a good level?

Have a good rest time. Good sleep makes miracles. Take a 'holiday' off your usual life. For hours, day(s) as often as you can afford. Getting 'out' of routine can be hard, but once you step 'out' you will appreciate.

Just 2 cents

Exercise at least 3x/week. Going to be early enough to wake without an alarm and be well rested. Eliminating alcohol consumption. Eliminating caffeine, sugar, and simple carbs and the concomitant crashes.

More productive than what or whom? What is your baseline?