While reading Epectitus definitely helped (externals - out of your control; reactions - your choice, things don't bother you, you bother yourself), and telling myself that I gain nothing out of anger (mostly lose from it), I ran out of fucks to give. Someone's blocking the way? Just wait until I can pass them. My delivery is running late? Whatever, it'll get there. I left the window open during heavy rain and everything is wet? Close the window and mop it.

In a world where nothing really matters, giving your undying attention to stupid things like these is just absurd. Who's watching your reactions so that you have to put on a show?

But as someone said, it takes practice. Being mindful, present, realizing that you're getting angry, and then consciously thinking "ah whatever" and accepting it. Difficult at first, but as with any skill, the more you do it, the easier it gets.