I tried the Kirsch protocol for frozen shoulder, which involves hanging off a chin up bar for 30 seconds at a time with a minute or two rest for 10 minutes a day.
Within 4 days my frozen shoulder felt tremendously better, I could move my shoulder above my head and behind my body pain free. Ido Portal loves this method, and it works incredibly.
I love it, so simple! Any gym or playground will have chin up bars, otherwise find a tree.
I hope this helps someone with the same poor shoulder flexibility!