Oh my gracious - these pants are awesome!  They are super-soft and stretchy and actually quite flattering, even for my plus-size self.  You will have no problem working out in these, no matter what kind of exercise you do - yoga, running, biking, weight-lifting, etc.  And you'll look good, too!  My only gripe is they're a little long - I'm 5'4" and I had to roll them up a bit.