Stand on a platform with one foot with it pointing slightly outwards.
Bend your knee to approximately 90 degrees and bring the other leg back.
Extend back up to the start position and repeat.
Knee caving in past big toes.
Using momentum to drop down.
Bending the back.
Holding dumbbells in each hand, place one foot on an elevated surface and have the other foot hanging off.
Start by bending the active leg and as you lower bring the other leg backwards to avoid it from touching the ground. Go to approximately a 90 degree bend or as far as comfortable then press up back to the start position. Push your hips back and keep a straight back as you descend. Your knee should bend in line with your foot. Repeat for the desired repetitions, then switch sides.
Avoid having your knee cave inwards past your big toe.
Fitness for all, for life.