A key for my longterm sobriety was grasping that this was a decision for life. Before, I'd quit for a month a couple times, but always figured I'd prove to myself that I could quit "whenever I wanted" then resume drinking under control. Somewhere it clicked that there was no future for me with alcohol, and I needed to accept a life, and lifestyle, without it. Wish I had figured it out earlier, because 20 years of my life was built around accommodating drinking instead of accomplishing great things, but better late than never. I got sober at age 39. It's gotta click: I don't drink anymore, forever.
Given some points on this thread, I also feel a need to be honest about how other people will react to you no longer drinking. This of course varies from person to person, but here's my story. Me and my family definitely lost friends as a result of me no longer drinking. We had family friends who also drink too much, maybe even abuse alcohol, and they were clearly uncomfortable with me not drinking at multi-family parties and other get-togethers. In no way did I become preachy or even comment about their drinking or otherwise wear sobriety on my sleeve, I just politely passed when offered. A number of them, usually drink in hand, however brought the topic of me no longer drinking up with me frequently. In my opinion, concern about their own drinking made them feel uncomfortable around me, and three years later, we're persona non grata with these folks. Their absence doesn't bother me in the least, but I think it's been difficult for my wife at times. This ultimately was a consequence of my drinking, and though I absolutely wouldn't give up one day of my sobriety for a lifetime of commiserating with said folks, I think it would be disingenuous not to be honest about it.