Choice definitely plays a part in staying sober. I can chose to drink or chose not to.
Even though I am not drinking now, if I was to go back I would be dependant on it again. I'm pretty sure I would start where I left off. After the very first sip, I know I wouldn't stop.
I still do think about drinking even now and I have been sober for 18 months. However, I don't think in terms of just having one drink. It is in terms of bottles. Did I chose to become an alcoholic? Nope, I sure didn't, but I do take responsibility for it because my choices did bring me to this point.