The easiest way someone explain this to me which really made it click -

Something potentially annoying or shitty happens... Think about how long it will actually matter for.

Will it matter in an hour? Will it matter in a day? Will it matter in a month? What about a year?

The longer it actually matters for, the more emotional effort you can feel justified putting into it.

I guarantee that the dogs tracking muddy footprints through the house won't matter in an hour - and just answering that question for yourself usually takes all the charge out of your emotion.

If it will matter in a year such as something big like a relationship crisis that could upheave your life.... Well maybe it's actually worth getting stressed about.

The best part about this is you can actually lie to everyone else, but you cannot lie to yourself about how long it will matter for and just asking yourself the question has the effect whether or not you want to be angry and say yes it will matter.