Lean on a table using the arm that doesn’t feel stiff and relax your shoulders. Dangle the stiff arm at your side about 45 degrees in front of your body with your fingers pointing to the floor. Then, swing the arm in a circle about 1 foot (0.30 m) in diameter, repeating the motion 10 times to loosen the joint and allow it to crack.  If this doesn’t release the tension in the joint, try holding a 3–5 pounds (1.4–2.3 kg) weight in your hand as you swing the arm in a circle to make the stretch more effective. This is the easiest and safest way to stretch your shoulder muscle and has a very low chance of straining or injuring the joint. Stand with your legs shoulder-width apart and let your arms dangle to the sides of your body. Then, bring them to the front of your body and interlock your fingers with your palms facing down. Slowly raise your arms in front of you until they’re above your head, and hold the stretch for 20 seconds.  If performed correctly, your palms will be facing the ceiling as you hold the stretch and your shoulder may crack as you raise your arms. For particularly tense muscles, raise your arms very slowly and pause as necessary when your muscle begins to feel sore. If you can’t interlock your fingers, hold a broomstick parallel to the ground in front of you with both of your palms facing down. Then, slowly raise the broomstick until you’re holding it over your head, and hold the stretch for 20 seconds. With your legs shoulder-width apart, raise the arm of the shoulder that needs to be popped until it is parallel with the floor. Then, move your arm in front of your body so that your upper arm is across your chest, and hold your elbow with the opposite hand, pulling the shoulder. Hold the stretch for 20 seconds or until you feel the shoulder crack. If you don’t feel any improvement, repeat the stretch 3 times before switching to the other shoulder. Stand with your feet apart and hold a towel in the uninjured arm. Drape the towel behind your back over the uninjured shoulder, and grasp the other...

TL;DR in Indonesian:
Lakukan gerakan pendulum untuk mengatasi kekakuan atau ketegangan sendi bahu. Atasi ketegangan otot bahu dengan meluruskan lengan ke atas dan menjalin jemari tangan. Dekatkan lengan ke dada untuk menderakkan bahu satu per satu. Lakukan peregangan menggunakan handuk agar bahu berderak jika Anda sedang mengalami cedera bahu.