there's really not much more to say than that, but being me, I'll expound anyway:
it teaches you to breathe. deeply. consistently. through tension and difficulty and discomfort.
it teaches you to slow down and pay attention. always.
it teaches you that you are capable of more than you thought. if you stick to it.
it teaches you that good things come with effort. yep.
it teaches you to soften your gaze, to be less demanding of the world around you.
it teaches you to move through layers of sensation, relaxing into each before moving on.
it teaches you that a calm and steady core diminishes the tendency to overreact.
it teaches you that the goal is not "not to fall," but when you do fall, to fall with grace.
it teaches you that balance is a necessity. balance between effort and ease, balance between stress and peace, balance between your body and earth.
it strengthens your muscles. making them look prettier. okay, and function more effectively.
it adds flexibility to your joints. especially the ones that tighten from hours of running and cycling.
it changes you, it calms you, it eases your path through the world.
it helps you to understand and learn non-resistance.
and perhaps, most importantly, it reminds you that we all share a common divinity, a common spirituality, a common core and bond, which is acknowledged with a simple namaste murmured at the end of each class. that which is divine in me bows to that which is divine in you.
yoga makes me a better person. it hasn't made me a better person: this is a work in progress, a work that is never truly done. but every small movement forward---and yes, the occasional leap---make it all absolutely worthwhile.