Lepium - I've had the exact same experience. I hate the idea of wasting a Saturday or Sunday recovering from a hangover because the entire time I spend getting my apps together and studying the GMAT time was so precious. Now I have this guilt or something hanging over me.
I had made a little guideline for myself that I wouldn't do any shots until my apps were, because my normal going-out routine involved dinner w/ friends followed by several rounds of shots (whisky at most places, ouzo at Greek restaurants, plum wine at sushi joints, or vodka if my Russian friends were dining with me) before going out on the town. So along with many other sacrifices, I gave up shots, but now that my apps are in I haven't really gone back to that because I know I won't be able to get up and go running in the morning and get a productive day in.
Really an amazing change that the whole process has brought about in that respect, and also in my general awareness of what's out there in terms of career and life opportunities.