Feel loose and heavy as you are doing it. Do this several times. Raise your shoulders as if trying to touch your ears with them. Up, back, down, and around. Do that about five times.
Some persons find it helps more if they roll their shoulders forward rather than backward.
Experiment to see which works best for you. Keep your jaw relaxed and breathe easily. Stand And Reach. Stand with your feet about shoulder-width apart. Put your arms over your head and interlace your fingers.