The viral chair challenge sounds simple. Put a chair against the wall, take three steps backwards and lean over the chair at 90 degrees. While you are bent over the chair, lift it up to your chest, and finish by trying to stand up straight with the chair in your hands. Kinesiologist Ken Best joins The Doctors to explain why this is easy for some people and impossible for others. He shares if you are not able to do this challenge, you might need to work on your hamstrings and glutes, and he shares a few exercises that are going to help strengthen and lengthen both.