I highly, highly recommend both yoga and meditation. I did yoga in the past and though have stopped for now (focusing on other exercises), it's something I will take up again. I'm not flexible either, but that's not important, there's a number of benefits to doing even the most basic form of yoga.

On meditation, I'm an active practitioner and do it daily. I actually do it more for spiritual purposes than for relaxation as many do, but regardless it's benefits are well known. Actually, I've created a Youtube video specifically discussing the benefits of meditation and the basics of getting started. If you're interested in seeing it, please don't hesitate to PM me and I'll send over the link (I presume it would be against the rules for me to post it here).