stop

× After he stopped to smoke, he would never smoke again.
√ After he stopped smoking, he would never smoke again.

There’s a difference in meaning between stop + to infinitive and stop + verb-ing. Stop to do something means that you stop doing something and you do something else, whereas stop doing something means that you don’t do this thing ever again. Compare:

• He was walking home when he stopped to smoke a cigarette in the park in front of his house. (=He stopped walking to smoke a cigarette.)
• Last year he had some health problems so he stopped smoking. (=He didn’t smoke again.)