When making decisions on how to spend my time, I try to balance three things: health, experiences, and career.
I try to do everything with the long term in mind; what will make me the most happy when I’m 80? Obviously I don’t want to be wheelchair-bound and on a bunch of medication so I prioritize health first. Get enough sleep, eat right, and exercise regularly. I find this also makes it a lot easier to study and enjoy myself. My remaining time I budget between experiences and career. When I’m old, I don’t want to remember my youth being spent studying and working, but I also don’t want to be working a dead end job. I’d like to be comfortably retired. I make sure I go out and have fun, but also I work hard and keep grades up. Of course, it’s not necessary at all to have perfect grades; both a 90 and a 100 are A’s, getting those extra 10 points does nothing to improve your grade, so why try for it? Better to spend that time on gaining new experiences.
With careful management and good work ethic it’s possible to have high standards of work while also having time to enjoy yourself.