I would have to say that according to the LOA, it is probably not the act of giving, but the vibration of giving. When you can be vibrationally aligned with giving, then you are at a vibration to recieve. It is the fear and the worry that keep us from giving as well as receiving.

If you are gripping something so tight that it can't be pried from your hands, then neither can your hand be opened to receive.

It is not for us to understand exactly how the spiritual aspect of things work together to manifest our desire, but it essential for us to know how to create, and to manifest our desire to get what we want for our self. So, the key here is to believe it, and you will see it. Remember this “Faith as a grain of mustard seed etc.”

We get when we give for the vibration we place ourselfs in when giving is like a vibration for receiving. Like attracts like and if we habitualy give than we shall create a momentum and habitualy receive.