Sharing personal possessions lets other know that you like them and also what you like and dislike, and can bring extrinsic (from the outside) and intrinsic (from the inside) rewards.
You want to share an extra tennis racket with your friend, you need to know how to offer it and trust she will not damage it.
Approach the other person, offer the racket and trust they will not damage it. When you need it back, ask politely. If your friend damaged the racket, you should take precautions next time when lending it out.