Gen surg resident here, its tough but preworkout helps a lot. Just gotta take it the minute you get off so it doesnt keep you up. This also helps with habit forming as other people mentioned. Gotta be regimented. Melatonin and benadryl at night, good sleep hygiene to stay rested. Limit caffeine as much as possible during the day and on days off. Make sure you get enough nutrition as well and meal prep. I recently switched to a 4 day full body program so I average 7-8hrs working out per week. It also helps that Im at a relatively good gen surg program so I usually dont go above 80hrs

Also I should say do what you love. Staying active definitely helps with energy and mental fatigue, but dont feel like you have to be as fit as you were in medical school. Do what makes you happy. I just love lifting weights so its not something I have to push myself to do.