Like others here, I didn't use any special mental tricks. What I seemed to do naturally without thinking about it, was that I kept paying attention to the achievers in my AA group, those who had achieved years of sobriety and were outwardly joyful. I was aware of other "old timers" who had achieved long term sobriety, but who confessed to it still being hard, but I kept watching the joyful achievers.
Early on, I was taken by their example of joyful long term sobriety devoid of struggle. It did not expect to meet such people. Intuitively, it seemed like a weird contradiction..., but it's what I wanted. I idolized them and used them for my role models. I gained confidence from them, accepting that such a life was within my grasp.