Try skiing, it is really fun, and if you haven't done it before, you will see massive improvements in your first season; it is very rewarding.
Other than skiing, I would probably suggest sailing. Sailing is usually complex, one has to learn about all the different sail settings, etc., but if you get to a sailing club that will either offer lessons in crewing on a catamaran, or has a catamaran team who needs someone to crew then it can be very exciting. Once you get a good sailing team in a catamaran, with a force 4 wind behind you, it can get pretty fun; especially if you are out on the trapeze.
Angus Higgins