I'm really hard on myself even for small things like missing a turn that takes me 5 minutes out of the way. Or making a minor mistake in my morning breakfast routine that I've been optimizing for 3 years. It's just how I'm wired.
(Having said that, restarting a game over and over in order to force your one perfect linear optimal plan to eventually work out can be lots of fun. But this is not an option in real life.)
While I'm on the cheesy aphorisms, I'll throw in "life is what happens while you're busy making other plans". But that one's too pragmatic, I think. It's not as if we have zero control. Maybe a more accurate statement would be "life is what happens while you're busy making loosely similar plans".
It is possible to lessen the effect of these things if you put effort into it.