All the 3-D Motion Research I do keeps pointing toward the inability of the amateur golfer to rotate their hips through impact. Most amateur’s hips are barely open at impact. Tour player’s hips are 35 to 50 degrees open at impact. When the hips are not open enough at impact the arms pass them up too soon causing fat & thin shots. Yoga or Pilate’s class at the Gym will go a long way to improve your flexibility. So you should always have a once a day stretch routine to help your flexibility.