P90X - Preseason - Day 3 - Shoulders/Arms

So far I think this was the toughest of them for me. Reason being is that I've never been an arms guy and I've had problems in the past with my left shoulder popping out.

So fortunately over the last 2 years I've been doing yoga which has stabilized the left shoulder but I am still wary of beating on my shoulders.

Also, I've never really worked the arms much in recent years...so there is a lot of weakness in...