Have you ever seen that one Elmo DVD where the mean man takes everything away from people? He always says “MINE!” and snatches someone’s toy? Elmo’s blanket got taken in this one! So sad! We know how hard it is for kids to share and how difficult it is for children to deal with others who don’t share. So, what has worked for you? You know you want to SHARE!!!!!! 
My son understands (usually) that sharing is REQUIRED if he wants to keep his toy: “You can only have that toy if you are able to SHARE that toy.”
So simple and perfect. Thank you. I will be using this one!!!
I do the SAME excat thing and it is a succesful strategy.