In reply to ctodd:
If youve never tried before go to a few different places before committing. You need to find a style and teacher you like, and there is huge variety!
Im currently doing my teacher training at the Yoga Space, in Leeds (Meanwood). Most classes there are Ashtanga based, where you dont stop and move from one posture to the next. More vigourous than other forms of yoga as a result, but the physical practice builds flexibility AND strength.
Worth a look I reckon. Good luck.