To do the Step Down, start standing on a bench or box. Stand close to the edge so that you can step off of it to the side with one foot. The higher the box you use, the bigger the range of motion you can do. You can also decrease the range of motion if you aren’t yet strong enough by using a lower box or by not sinking all the way down. You do not want to go too low and end up setting your foot down on the ground so that you can push off.
Standing near the edge of the bench with your other foot right on the side or hanging off, slowly hinge forward sitting your butt back as you drop the foot on the side down toward the ground. Keeping your back flat, push your butt back as you bend your standing knee to drop your foot toward the ground.
If you can, lightly touch the toe of the foot to the ground, but make sure you do not drop it all the way down so that you can push off of it. Sink as low as you can then drive right back up to standing. Make sure you are only driving through your standing heel and not using your left foot on the ground.
Do not rock forward as you come back up to standing. Really use your glute and drive through your heel. Stand back up nice and tall and squeeze your glute at the top.
Then repeat, sinking back down.
Go as low as you can and complete all reps on one side before switching.