Yoga is great. Good for all sorts of things - flexibility, strength, body awareness and coordination, relaxation. I do it several times a week, mostly to keep my back limber. I used to go to a class (no time now) where there were many girls, but also several very fit runners, cyclists and a bodybuilder, who all used it to complement their chosen sport.
I've been doing it on and off for many years and thoroughly recommend it. When I was doing triathlon it was great for working the kinks out, and a good general stretch before an event.
Find a class, give it a go. There are lots of styles available, probably best not to go for Iyengar or that sweaty yoga first of all. A good teacher will not insist on you being able to get into the exact pose - ours used to say "it's the journey, not the destination", and no-one in the class should make you feel uncomfortable, (apart from yourself).