I seem to remember hearing somewhere that thinking about something X number of times (I forget how many) wrote the same mental pathways as having done it once. This was used to caution one against contemplating evil, and encourage the results of contemplating good.
What I don't recall ever hearing is the danger this poses to housework. By that logic, it only takes X number of times thinking about, say, washing the dishes, before you feel as if you have already done them.
And what could be more depressing than washing dishes that have already been washed?
Clearly the only solution is to stop thinking about washing dishes, so that one is not deceived into believing them already washed.