I'd suggest writing or artwork, but that too is rather work-like, isn't it? Just kicking back with some computer based games here and there couldn't hurt. I find the trick is to have several things you like to do, so you don't get bored just doing one or two things time and time again. Draw, write, create, go for walks, read a book, enjoy a bath, watch TV, play a game, have friends over for board-games and supper, that kinda thing. :3

There's always farking around on the internet too, with such mediums as chatting and SL.