Hi Alice, welcome.
I've found that you don't get willpower. Not in terms of bucking up and tapping my ego-self anyway.
As an atheist, do you feel any spiritual connection to something in your life? When you take a walk in the woods or something similar, is there a sense of wonder? When I was drinking I was totally disconnected from the beauty and soul of what was all around me. In strictly technical terms, I guess I'm an atheist as well. But through meditation, spending time outside, and working with others I feel a connection now to something greater than me, something mystical. To paraphrase Bill Plotkin, my conversation with the universe has gotten larger. I find God there. There's a poster on these boards who goes by Ago -- some of the stuff he's written on his atheism paints a picture of what I'm getting at rather well. There's also someone here who identifies as a pagan witch who draws her strength from Gaia, or Mother Earth. I think that's awesome too.
There's a strength in these connections that supersedes will. It's very powerful. My drinking and sense of constant unease I believe came from a long disconnect from that power. Finding it again has changed my relationship to both myself and those around me, where the urge to drink that dominated my entire life has faded into the distance. I've been rescued from myself; I've been rescued from my willpower.
There are many, many roads to finding this connection. Best wishes.
Chris