My understanding of it is that the psilocin sort of mimics serotonin and ends up binding to those receptors instead of your serotonin. Your brain is then all kinds of fucked up. Because of this your brain is forced to use different pathways rather than continuing to entrench your current ones - quite literally getting you out of a rut. The other bonus is that unlike other drugs like MDMA or even LSD to an extent, none of your natural chemicals are depleted. It just wears off and you’re back to normal.