“Whatever you focus on increases.”
There are a million versions of this idea out there; the above is sort of mine but mostly Laura Doyle’s. The link is to the post I received today, but she’s said this many times, in many contexts.
There’s some real truth (as opposed to unreal truth?) in this saying, but I want to focus first on how it can be false, since we humans always take thing too far. It’s false if taken in the sense of magical thinking, the idea that your thoughts can actually change external reality–“If I think this hard enough it will come true.”