Can you keep your butt untucked and your back neutral (allowing the lumbar curve to be present) and relaxed?
Try to keep a slight lift to the bottom of your rib cage. Avoid bracing hard with your abs (that tends to pull you into the rounded back/ butt tuck), but there is supposed to be some space between your thighs and your body. Again, it can be a tricky balance to find, so experiment, and if you can use a mirror to really see how your body is moving, that’s a great tool!
Now let’s do the no-cheating version! No matter how diligent you are, this squat is a hard shape to figure out. I LOVE this version for its illuminating boundaries.
Stand with your feet under a chair and make sure your knees are touching the edge of the seat when your legs are straight. Hinge your hips back more than down. Keep your upper body lifting slightly away from the chair to help manage the tendency to drop too low and over-hinge the hips and under-hinge the knees.
Stay in a position that doesn’t strain ANYTHING! Not your knees, your back or your neck. If you feel strain, come up a bit and let your shoulders and neck and head soften, without rounding into your lower back.
Try to hold that squat for 60 seconds, or as close to that as feels right for you. Having done that, try it again without the chair and see how it goes!