From a blog post by Gregor Maehle:
Pratyahara means that practice-wise we stand on our own feet. We do not practice because of the amazing teacher. We do not practice because of the support we get from the outside, from the community around us (although we may take that as nice boons if it works out but shouldn’t compromise when it doesn’t). We practice because deep inside we actually want to. Because the practice (in its many forms, not just asana) brings us back to that place within us where we are whole. So practising yoga is nothing but a return to our origin, a return to our own heart, or the self, in Emerson’s words.