I'd say the ease which you can pick up habits or drop them is extremely variable across the specific habit and person. (as a different example, someone with less social awareness will find it harder to pick up the habit of being a hospitable host than someone it comes naturally to, but once learned its probably fairly easy to maintain)

One of my favorite quotes is, "first the man makes the habit, then the habit makes the man" , and it works both ways, good and bad. I really think this is something that should be taught much more explicitly in school to everyone, rather than leaving it only in places like sports and the military.

It's important not to ruminate on bad thoughts (when your proposal is a good replacement behavior), but it's also important not to bottle up natural human emotions as if they are unjustified or unreal.

A thought exercise: if it wasn't your behavior that caused your own despair, but your spouse's behaviors that caused you irritation / grief. Do you think it's better to paint a smile on yourself and ignore the underlying problem, or spend a few minutes feeling your emotions, describe the cause to your partner, then politely suggest a substitute behavior? The former builds resentment and bottles up strong emotions for an inevitable outburst down the road. The other diffuses the emotion, potentially alleviates the offending behavior, and doesn't betray what you authentically emote.

https://www.youtube.com/watch?v=0K8lrVjT6fM