I didn't think about the lifetime ahead when I was nearly sober, I focused on the day to day, that's all you have to do. I couldn't contemplate the whole future without alcohol, especially not in the beginning, it was too overwhelming.
I actually find it much easier these days though to be completely abstinent, rather than stopping and starting all the time. That pattern knocked me around a great deal mentally and emotionally, and can make you pretty discouraged. I'm not criticising anyone here, but I did it myself, and put myself through a lot of pain that way.
We all have cravings in the beginning, that's a part of withdrawal, and the mind starts looking at ways to rationalizing a drink. In time I learned to recognize them as cravings and let them pass (similar to AVRT method). All I could think/obsess about in the beginning was how much I missed a drink. If you stay stuck there though, don't move on to other interests, it really is difficult, that's why it's so important to actively engage in recovery. If you look at the 12 steps, only the first is really about alcohol, the rest is about building a new life.