I won't bore anyone with the background, but in my log you can see I struggled with RC pain and severe AC pain which only ended with a big fat cortisone and lidocaine shot and a few weeks off. I started doing some shoulder rehab excercises but they seemed to hurt a bit too much. I did RC excercises religiously too. A month ago I got a bright idea and I have been lifting hard (chest and shoulders 3-4 times a week) without any more pain issues since that time. As a warm-up I take a 2.5 pound plate in each hand and gently begin to do my entire range of motion - arms extended, at sides, hi, low, etc. I then hold my arms out straight to the side and rotate them (that hits the RC lightly). After that I lean over and retract the good old scapula while I let my arms hang down to the floor and stretch for a few seconds. I keep extending my ROM gently and repeat this a couple more times, preferably while watching Univision. I then do a short variation of this in between every set, or every second set, depending on what I am doing, how I feel, and how heavy I am going. Just throwing it out there, YMMV, someone will probably point out that this will give you cancer and AIDS, etc. But it has worked for me.