Chair pose strengthens your knees by targeting your quads and hamstrings, which, if tight, can lead to knee pain or even injury.
To sink into your imaginary chair, start in a standing position with your feet together and your arms at your sides. From here, bend your knees, sink your hips, and sweep your arms overhead. Gaze down from your chair position and be sure that you can see all 10 of your toes. If you can’t, pull your knees back further. Stay low in chair pose for 3-5 breaths, then exhale and release to a forward fold position.