Do this in a kitchen. Stand sideways to the counter. Put a hand on the counter (the lower you can grab, the more resistance you will get, someday I will try this on steps). I also use a small weight.
Rest a hand on the counter, lift a foot (you will do both feet, then turn around and do the other side) and then let your torso bend into a C shape. Bring your torso back into a neutral position with your torso and leg muscles, not your arms.
I also walk forwards, backwards, and sideways against bands. I have some very thick bands, so when I do this a lot, I get tons of resistance.
You will use less resistance sideways, there is also a trick. You step sideways normally, but then use your torso muscles to bring the trailing leg back in.