I started teaching group fitness way back in the 80's, started my own personal training business in the 90's, began practicing yoga in 1992 and started teaching yoga in 2005. I like teaching a beginning/intermediate level because if alignment is paid attention to then most injuries can be prevented, and yes, you can hurt yourself in yoga. My Pilates classes are mixture of Pilates and good old fashioned strength exercises.
I believe that the more you move the more you will be able to move, and the less you move the less you will move. I also believe that yoga, like life, is not perfect and we shouldn't expect them to be so.