if i had a dime for everytime i heard, "i'm not flexible enough to do yoga," i'd have lots of dimes.
the quick yoga lesson of the day is that yoga helps your body and mind be more flexible. it helps you figure out how to exist outside your comfort zone because although some poses may seem awkward and definitely uncomfortable (especially if you're a newbie) it you can figure out how to be calm in that moment and stay in that pose for a few breaths, you'll be much better equipped off the mat when uncomfortable situations arise that can last longer than just a few breaths.
the great thing is, if you're not super bendy, that means you'll have to go less deep into the poses (read: stretch less) to still reap the benefits, while some other yogis may have to morph into a pretzel to feel the same level of intensity.
there you have it, less flexy doesn't mean yoga works less for you, it just works. it's an all or nothing deal, if you yoga, it will work, if you don't, it won't.