My two main hobbys are bodybuilding and fishkeeping.
I like bodybuilding because i'm a wonderful tinkerer. Everything that i own has to be carefully locked away or have big signs written around it or i'll end up sequestering it for a few days to have a poke around with a screwdriver or two.
Since bodybuilding is never something you can fully finish, i can spend all the time in the world thinking about what exercises i can do, which bodyparts need to be brought up e.t.c. Granted it takes a little longer than destroying something with a screwdriver and attempting to put it back together again before throwing it away in anger, but hey, at least i look good from it.
I like fishkeeping because they're so cool! I love my little fishies so much, i don't take as much care of them as i wish to right now because i'm suprisingly short of cash. Fish take a lot of money to look after properly.
At the moment i've got two tanks, one with 3 axolotls, and another with a few tetras and shrimp (which i'll be emptying soon, most of the fish have died from old age). When i get enough money, i'm going to build a covered pond and fill it wish tropical fish, that will rule!
I also have a couple of other minor hobbies, such as taking pictures of everyone i know (i'm bad with remembering faces) and writing reams upon reams of poetry at silly hours in the morning, and juggling, i like juggling.