Man is nothing else but what he purposes, he exists only in so far as he realizes himself, he is therefore nothing else but the sum of his actions, nothing else but what his life Jean-Paul Sartre, 1965.
It is clear that there is no such thing as an independent, invariable self. We are human becomings. Our experience of ourself is that of a human being but a fairly basic analysis readily demonstrates that we are not the same as we were yesterday, nor will be the same tomorrow. If we have free will, then we can shape this becoming by selecting our responses to the triggers in our environment and in doing so we can become the architects of our own evolution.
I eat a chip in response to a craving. I become the hot chip. I feel angry in response to an insult. I become an angry person. I laugh and I become the laughter. I am the product of every hot chip, every angry response, every laugh. Ever single thought, feeling and action has merged together to have me emerge as I am right now. I will merge and emerge every moment of my life and even after death my body will continue to be part of the cycle of life.
If we have free will then I can select how I respond to the triggers of my life and in doing so I can take charge of my own emergence.