She straddles you, wrapping her legs around your body. You stand and support her in your arms. She can start on the bed and have you pick her up without disengaging. (Or for the truly bold, she can hop aboard from standing position!).
You need to spread your thighs slightly and not lock your knees. But if you have a bad back this is a very bad idea.
You push her up against a wall—very carefully.