Then lower yourself slowly at first to get comfortable with the movement. Bend your front knee as you lower, bearing most of your weight on this leg. Your knee should not extend further than your foot. Step out further if this is a problem.
Then push off that foot and come back to a standing position. Repeat with the other leg. Continue until your legs are too tired to complete correctly.
As your comfort with the movement increases so can your speed and depth. You can also “walk” forward, lunging with one leg and then the other.
You can try an alternative lunge if you have injured or sensitive knees.
Stand with feet shoulder width apart.
Step back about two feet with your right foot.
Then lower your back knee towards the ground. Bare more of your weight on this back leg by leaning backwards and bending the right knee.
Raise up and return to a standing position. Then repeat with the other leg.
As your comfort with the movement increases so can your speed and depth.