oh, i forgot yesterday to post what i actually wanted to post. something constructive:
try to start something new. preferably something you thought about for a while. when we broke up, i noticed that i have too much time and energy left over, and that only harm can come from storing it up for some moment to explode. so i started working out. pushups, pullups, situps - usually during the commercial breaks of movies. i took the whole thing further by going to a gym regularly and training muay thai (something that had me itching for years on end but took that "i dont care about anything"-mindset to get me started).
long story short: it is indeed hard to be in the blues 24/7 when you feel better in your body than ever before. still, the downs come, and they will hurt, and they will most likely be haunting you... but having some ups to counter them, even just to have some un-down moments, is worth its weight in gold.
if physical exercise doesnt float your boat (a good side effect of it is that you fall into your bed too tired to do anything), maybe there is something that has such an effect on your mind, a special drive of you, whatever. just keep doing you some good. it keeps you doing something (even the dumbest purpose is better than no purpose, now) and it makes you get something good done to you (which you sure are in dire need of).