For example, I'm a software developer. To become good at what I do I've developed a habit of rapidly thinking through possible execution flows whenever I write a routine. I especially tend to imagine what will happen in "bad" situations, and what will cause failure scenarios. What if the array is null? What if it's just empty? Etc.
Developing a habit of thinking like this is crucial for being a good programmer. However, this manner of imagining failure situations is generally bad in the real world. I notice myself doing it from time to time (more often I've been working a lot). Today I caught myself in an empanada shop wondering where I was going to go to get change for my 100 peso note if the empanada man didn't happen to have change (Argentina has a significant change shortage). I was worrying about this before it was even time to pay. It ended up being no problem at all. Had it been a "problem," I could have easily just found a solution after the fact and not wasted time being concerned beforehand. It wouldn't have crashed any servers, exposed private user information, or gotten anybody fired.
So, that example happened to be a negative one (although it's not so bad to train myself against). I can name plenty of positive effects too, but I'm more curious what other people have to say.
For example, I talked to my girlfriend who convinced herself for some reason that she needs to lose weight. She mentioned a number of things she could do towards that goal. She wanted to start working out, or start counting calories, stop eating deserts, etc. My first instinct was that the first and most important thing you should do if you want to lose weight is: Buy a scale and weigh yourself every day. All the other things I viewed as secondary.