Forward lunge

Directions:

Stand erect with your feet hip-width apart, chest out, and shoulders back, maintaining the natural curvature of your spine. Your knees should be unlocked and your hand on your hips. This is your starting position.
Take a moderate-length step forward with one foot, descending to a point in which your rear knee approaches the floor without touching, maintaining your body's upright posture. Your front knee should bend about 90 degrees, but for knee health, it should not be forward of the vertical plane that extends straight up from your toes. If so, take a slightly longer step.
From the bottom position, push back up from your forward foot, bringing it back beside the other.
Repeat on the opposite side for the required number of repetitions.