Walking in the city (I live in NYC). Doesn't seem like exercise at all, but I can easily walk for hours without getting bored here. Obviously I can't do that everyday, so I really enjoy the treadmill at the gym or squats at home (they really help me build stamina but squats alone don't make me lose weight).
My fav is yoga, in tree stand position. Loved it totally.
i like walking.. walking while chatting with friends in order to make it more interesting