One leg squat with box

Starting position:

Prepare a box of appropriate height for your fitness level. Stand close enough to the box to hint at sitting on it. Take a posture with feet slightly more apart than shoulder width, without rotating your toes to either side. Lift one leg forward, slightly above the floor. Fix your posture and keep your pelvis in a neutral position. Stretch your hands forward but do not lift up your arms.

Exercise:

From the starting position, inhale and go down by flexing your knee and hip joints without changing the spine curvature. Guide the knee of the working leg straight forward in the direction of the toe position. Slowly sit down on the box. Keep your body core firm and do not bend forward too much. Go back up the same way and exhale until you get to the starting position. Keep the non-working leg in the air slightly above the floor throughout the movement. Keep your hands stretched forward during the movement. Do the required number of repetitions using the same technique and then switch legs.

Remember:

Pay attention to your body posture, fixing your body core and keeping your pelvis in a neutral position. Avoid over-bending your spine. 

Keep your knee in the direction of your toes throughout the entire movement to prevent it from swinging to the side when overcoming the resistance. Also pay attention to the knee movement of the working leg and make sure that the knee, trunk and head do not go beyond the plane of your toes.

Make sure you do not bend forward too much when you squat downward.

Recommendation:

Exercise sideways to a mirror to check and correct the technique.

To make the exercise more challenging you can gradually lower the box level until you do not sit on the box at all.