When I was an undergrad at CMU, I learned how to work hard. Really hard. After having coasted through too-easy high school, I spent all day every day at CMU either programming, doing mathematics, or thinking about one of those things (to great effect: often the trick to prove a theorem would pop into my head while showering or while taking a walk). I would fall asleep while programming in the middle of the night, dre…
This was exactly my experience except Masters instead of Bachelors. I had this feeling that I mostly coasted during my bachelors, only putting any effort the week before Finals or Unit Tests. I did my Masters in EE from a university renowned for being a tough program. I was up for the challenge, doing exactly what you did: thinking math all the time, feeling like I was wasting time any moment I was not in front of my…
There are university programs where you can coast through a degree, and others where doing that will at best leave you at the back of the pack.
It can be fun to be in a program where everyone is pushing hard but it can also be very stressful and not healthy for everyone who tries it. It is possible to live the rest of your life like that, but the vast majority of people I know who have tried it, aren't happy. The exceptions are outliers in several ways.