"Retreats are not ordinary time pass events, they are game changers of life."
See, when you feel depressed for one hour, you have made a lot of (18 billion) new nerve cells with a "feel-bad" type "receivers" on their membranes. It is as if they are saying "send us more feel bad peptides" .And they multiply.
Meaning, new cells are created in that big number, according to what you think and feel,
and how you live your life moment to moment.
That is it.
That is why you see so much suffering and diseases. And that is an untrained mechanical , tired mind. A zen retreat which is training in the right direction is a god sent opportunity for us.