I used to do yoga on a regular basis - it is really great if you find the style that works for you and a good teacher. I did Hatha yoga - not too tiring but really stretched my body. I always said it should be free on the NHS!
I can't make the class times now and I seem to have little time these days but I would definitely give it a try. Don't give up if the teacher is rubbish - find another class. I really noticed how my body had lost flexibility in the times I stopped before I restarted.
I don't do Yoga but I regularly do Pilates. The exercises are similar as they involve eccentric muscle movement. i.e. They strengthen the muscle in an elongated state.
Another way of thinking of it is to look at a ballet dancer. Every movement involves control of the limbs as they return to a neutral position. A weight lifter, by comparison, is measured by how he lifts a weight above his head, not how he brings the weight down and returns it to the floor. He just throws it away.
Raising weights is concentric movement as he tenses his body and contracts the muscles. That's not what we want. If he was measured by how gracefully he returns it, he would need to use the muscle eccentrically. That is what Yoga and Pilates give you.
If your muscles are too tight then you can get some benefit from magnesium or a drug like Dantrium. They will loosen the muscles but that will expose how weak they have become. Yoga or Pilates will work synergistically with muscle relaxants to rebuild strength in an elongated muscle state.
Don't underestimate the benefit of massage to ease muscles before you exercise. Hot rocks or heat packs on a towel left to soak the heat in to you can ease muscles as part of massage as well.
Definitely do regular eccentric muscle exercises.