Higher education can be very demanding, indeed. I did it full time for six years, and I've been at it part time after that for more than I'd care to admit. When I was an undergrad, and later a graduate student, I solved all of my academic and most of my life problems by simply working harder. There was neither rest nor play until the work was done. That was non-negotiable - a hazard of New England Puritan roots, I'm afraid. What I didn't realize until just a few years ago was that having some non-work related element of joy and solitude in my life on a consistent basis made me far more effective at school and work. The trade off of a few hours spent tying flies or swinging them on the water was greatly enhanced productivity the rest of the time. Yes, devote the necessary hours to the books. Unless you are freakishly gifted (and even if you are), success is still largely proportional to the time you spend with nose to the grindstone. But don't put the fly tying vise, rod, and reel into deep storage. You may find that in small doses, they actually help contribute to your academic success.
"It don't mean a thing if it ain't got that swing"
- Duke Ellington