My love for Urdhva Dhanurasana stems from a long and troubled relationship. I have been practicing this asana, or trying to, since I first began rolling out my mat on a regular basis almost three years ago. It was included toward the end of the sequence I practiced from Linda Sparrow's The Women's Book of Yoga and Health, so I tried it every time I practiced, in spite of the pain and fear.
Early on in my yoga adventure, I had a tendency to think that every struggle I faced on the mat was the result of a lack of strength, be it physical or mental, so I muscled my way through many postures that I should not have attempted at that point in my practice. I was not ready for Urdhva Dhanurasana, and it was not because I was weak. It took me far too long to realize that much of my trouble in UD was due to tension in my shoulders and chest, and because of this, I strained, slipped out of the pose, and hurt my right shoulder a few times before I figured it out. But, alas, I did figure it out. I have been slowly and carefully working on opening my shoulders, and the change in my Urdhva Dhanurasana is enormous.
These days, I practice two or three Urdhva Dhanurasanas every time I hit the mat (with the exception of restorative days), and it's always one of the highlights of my practice. Just in the last couple of practices, I've played with lifting one leg. I haven't tried fully exentending the lifted leg -- I'm still just feeling out where my support is going to come from, but I'm hooked on the energy build of the backbends, and nothing electrifies the entire body like a big backbend.