Wall Sit - Single Leg
The single leg wall sit is significantly more challenging the the double leg version. It requires more hip strength to stabilize the unilateral position and the knee extensors of one side must support the full load of your bodyweight.
Cues:
Position yourself so your knees and hips are each bent to 90 degree angles
Keep your heels down and low back against the wall
Slightly shift your weight to one side and raise one leg off the ground
Scale by raising your torso higher on the wall
Mistakes:
Shifting excessively to the side to find balance
Arching the low back off the wall, or losing heel contact with the floor
Forcing the full position and causing pain when you should be scaling to build strength more gradually