When I first thought I had a problem with alcohol, I never considered I'd be able to quit. I was the "life of the party" it was in my identity, but deep down I knew I had to quit.
I eventually heard a friend of mine back from the "party days" who was just like me was able to quit drinking for a year. I decided to reach out because I could finally relate to someone (not that I had done much looking at that point).
He told me how he did it, and that embarked me on the journey of sobriety: while I had a few starts and stops (failure), I've finally managed to string quite a long sobriety together.
Whenever I have issues, or feelings I can't quite shake or cravings, this is still the person I call.
So in summary: seeing someone that was like me, that I could relate to encouraged me to think that I could do it too, and inspired me to continue seeing how much better their life was.