One of the apparent functions of the perception of one's will is to make one's own action predictable by the self. By the cognition of the fact one is about to conduct an action, one is able to prepare oneself for the likely outcomes of that particular action.
For example, if, on a hot summer evening, one wills that he opens a can of beer, he can fairly well predict a series of sensations that follow. The feeling of the tab being pulled away, the sound of micro-bubbles forming in the can, the first taste of the desirable drink on one's lips and tongues, the flowing of the cold liquid down the throat. With appropriate predictions, these sensations can give one a great pleasure, as this writer is very well aware.
Without prediction, however, the same series of sensations can be a source of anxiety and horror. Imagine, without you knowing it, somebody abruptly puts some beer into your mouth. Shock and panic would be your reaction, rather than the harmonious joy that would follow the perceived action of drinking.
Thus, the perception of one's own action contributes to the stability of processing of sensations that follow. Every perception is conducted within a context. The perception of one's own action prepares the particular contexts.