Chances are, they’ll try to avoid acting on those impulses for you, for a little while at least. The issue occurs when they almost inevitably act on those impulses and you’ve now got a new problem to deal with, their guilt for disappointing you or breaking that promise. Guilt is now mixed with all of their other negative emotions they are feeling for having “failed” again. Fear, anger, despair, etc. etc. etc.
What do you do when someone you love or care about has an issue with impulsivity? It depends on the person, the impulsive act, and their triggers. Everyone is different and therefore needs different TLC.
It’s easier to say what you shouldn’t do.