I have a bit of a meta-question, but first let me give you some background. I used to be a very inquisitive kid, interested a many disciplines, in particular mathematics, computer science and physics. I have never been hard-working, or never had great focus, but I had a very good intuition and ability to learn, which propelled me through high-school and beyond with great success. I got into all universities I applied to, everything was great. Towards the end of high-school, however, I started struggling with depression. I did not worry too much about it at first (its main impact was on my sleep, leading to insomnia, etc).
During my years at university, however, it became rampant. Today I am in my third year undergraduate. My grades so far have been decent (averaging above 75%) but I feel I am not where I should be. It is very hard to explain in words, so I hope one of the person reading this will have personally experienced it, but I feel in a "braindead" state. I lack motivation to study my courses; I lack focus; I get nearly obsessed over simple concepts if I don't fully understand where they come from.
I would greatly appreciate if anyone could share a similar experience, or any advice as how to deal with it. I doubt reading a single paper will get me back on track, but maybe there are mathematical wonders out there, or enlightening blog posts which could guide me. I am sure many people have gone through similar phases.
Thanks!