Just about the time you feel real good about the work outs:
Back off, do [much] lighter weights and more reps...keep the tone, don't abuse the joints, and you'll stay happier longer.
And, screw the tennie-shoe advertisements, don't run on concrete any more than you have to.
It's the left rotator cuff for me - every time.
I refuse to listen to my body, I blow it out, lose interest in lifting, and I have to start from scratch 6 months later as a scrawny little dude. I never learn.