The concept is very well know in NLP too and it’s in some way an explication of the fact that winner (in all fields) tend to win always, losers tend to lose, some kind of people tend to live ‘next to’ the same kind of people.
The idea is that thinking and believing and acting in some way, can make things happen. This is not just for a magic, is because you tend to behave and your brain tend to drive yourself to the satisfaction of that thought.
Your state of mind MODIFY the way you perceive reality and than your activities, your reaction.
As an example, if your young son come back home REALLY late Friday night, here are two possible reactions:
State of mind 1: you think he had an accident. Reaction 1: when we will open the door, you’ll hug him and be VERY happy that he’s alive! Everyone will be happy and will be a great evening and a beautiful weekend.
State of mind 2: you think he was just out with friends and didn’t want to come back earlier. Reaction 2: when he will open the door, you’ll start screaming and kicking is a@@ (if you can 🙂 ), being really angry. For sure it will be an hard night and a bad weekend.
Same situation, different mind-sets, different reactions, different ‘mood’ …