Yesterday I suggested a momentum exercise in which you learn to use a sidestep to kill your momentum, leaving you in shizentai ready to move in another direction. This experiment is easiest to do walking forward by yourself at a moderate speed. Here's you a modification to make it easier to run this experiment walking backward.
Tie a rope to a wall or post at shoulder-level. Hold the rope with about an arm-length amount of slack in the rope. Start standing right next to the pole and walk backward until the rope snaps taut. As the rope snaps taut, put one foot straight under your hips and use the other foot to do the sidestep trick. Repeat this experiment over and over so that you can practice sidestepping to both sides at the end of the line.
Now, where this becomes really cool is when you replace the pole and rope with an uke. The Nijusan form of oshitaoshi and udegaeshi are done with tori passing backward right beside uke and moving away until the connection at the wrist snaps taut. At that point, if you plant one foot you will sidestep behind uke and execute an oshitaoshi very similar to release #1. If you plant the other foot, you will sidestep in front of uke, turning into kotegaeshi or udegaeshi.