Forever seems like a long time.
I know. Maybe it helps to look at it in qualitative terms, rather quantitative? Which do you think would be preferable: A life without another drink vs. a life where you drink, stop, drink, stop, drink, stop.....
The key for me was to stop looking at "forever" as a sacrifice, and start thinking of it as gift. If I were in prison, would I be afraid of being released forever?