Smoked for about 15 years, tried a few times to stop, never worked. Made myself a promise to stop once I get a dog. Got a dog and stopped smoking with no problem.

Possible contributing factors:

• When it was time to stop I was already pretty disgusted by smoking. I just needed a last push.
• My mind was in a more positive state after I had a deep depression for a few years. I was also more conscious about my health because of that (see previous point)
• My friend group and work place used to be full of smokers and somehow that changed over time, so I was often alone with my addiction