I have seen some posts math.SE (mkko's answer) indicating that it is the norm for (undergrad?) math majors to study 70-80 hours per week. I'm a little bit shocked by that. For some background on me, I'm not very advanced (only finished calculus 1-3 and taking my first DE class). However, personally if I am trying to solve a tough problem or prove a theorem, I can't work on it for more than an hour at a time without killing my ability to think creatively, which is the most important skill we mathematicians should cultivate, right? After about one or two hours, I can't engage the theorem in deep thought, so trying proving it becomes more of just an unproductive guessing game. If I just come back the next day, I feel like I have digested the problem much better and gained more perspective. When there is new material, I do spend multiple hours just trying to learn the material and become familiar with all the definitions and intricacies. However, I feel that it's most important to focus on problem-solving and proofs.
So my question is, what do these 80 hours a week consist of for typical math students? Is most of that time spent on trying to just learn the material? Is it actually spent on cultivating problem-solving skills but I have just have a really low tolerance for focusing? Is spending no more than 1-2 hours per day on the same problem optimal, but just a luxury that students can't afford once they reach a certain level?
I doubt anyone needs to put in 70-80 hours a week to get a math BA/BS, some people just really really like math and can't help but study it all the time.
If you find yourself burning out after an hour maybe try a different strategy. I put in probably about 50 hours a week and do micro breaks. Basically periods of deep concentrated study/thought, broken up by 10-15 minute breaks whenever my brain needs a quick rest, usually I'll check reddit or Math.SE or watch a little bit of some show.
Sometimes if I'm trying to understand something especially abstract or conceptually deep I'll go for a walk around the block and just ponder. These walks can be very enjoyable.
At your level you really just need to do lots and lots of exercises, however once you've done a couple thousand proofs, and gotten through the standard graduate level material, then it's more like exploration, and proofs and rigor become less important.
Everyone's different, and the study strategies which work for me may not work for you, but this is what works for me.