If you're comfortable giving up most of your social life, it's quite challenging yet still very possible (I did this for four years of undergrad). Time management is absolutely key, as Dr. Death said. It gets easy after you get used to a crazy schedule like that. But seriously, you either cut out social events or cut out your hobbies that keep you sane.
Edit: not trying to brag so please don't take it that way. Just wanted to back up what I say with my own experiences, n=1