What a great question I used to get it all the time, but haven’t for ages!
For me, the angst was less about the quality of the purchase and more about the quality of my decision, so I worked on that!
No impulse buys lots of research, lots of consideration of alternatives, opportunity costs, and unintended consequences. Sometimes just mentally, but for big things I talk it out with someone else or gt it down on paper.
By the time I pull the trigger, I’m confident that I’m making the best decision with the information available at the time, so there’s nothing to ruminate on!
Despite this, sometimes the purchase turns out to be less than optimal, but I don’t beat myself up over it. The decision at the time was good, and now I just need to make another decision on how to best move forward and make mental notes on what I can do better next time.
There aren’t too many purchases that are catastrophic even if it was a bad decision, learn from it and move on! Don’t fall for the sunk cost fallacy and pour good money after bad; if it’s a bad purchase, get rid of it!
Good spending also takes practice, particularly if you focus all your energy on getting good at saving! Work the muscle, apply the process to less critical buys, so when you get to the big stuff, it comes naturally!