Saying "no" to trying to read every single email you receive. Saying "no" to every new tech tool or idea you hear about. Saying "no" to every friends' request to hang out. Saying "no" to staying up later than you know you should.
I would also say, getting cut off on the highway or not finding the match to your favorite socks should not elicit any increase in your blood pressure. These are things within the right perspective can be put in a "not important" category.
Hopefully you get the idea and understand where I am coming from. This is not ground breaking or even research based stuff, this is common sense up to this point.
Here is where I will pivot a minute and explain that acceptance of those things you say "yes" are far more complicated and eventually struggle with. You do find these decisions important and therefore give time to accomplishing these decisions, actually bring a lot of problems.
For every "yes" and every effort you put forth, brings another set of challenges, one's that you accept because they were your choice. I am keeping this short, but just understand, from my perspective, that the "no's" and "calmness" during moments of trivial issues become the fuel to allow you to say "yes" and put forth effort to those things you find important.
Wasting all your energy on "no's" and trivialness will only allow you to tread water and you eventually feel like you are going to sink.