My advice is: forget the gym, forget the theatre. If you have to force yourself to do something, you probably didn't want to do it that much in the first place. I would suggest taking a good cycle ride around London. In cycle shops you can get an AMAZING cycling map of London for 5 quid - it's really worth it. Then go on the yellow paths and - if at all possible - some green ones (along the canals). My personal preference would be to light up a spliff along the way and take it nice and easy. Go to a market (whichever one, there are so many!) and buy great spices and food. Then, on your way back, pass by a pub - if on a park, all the better (London Fields is a good place) - and reward yourself with a pint. If you can find a CAMRA pub, then have a proper ale. When you get home, cook one of these recipes that appear in the Guardian or Observer and have a good meal. Finish off with a cup of tea, spliff and DVD. Office worker.