Use of Body, Mind and Money

Our body like machineries become worn out with use, or rusts (show changes) if not used at all. It also needs maintenance. But our mind does not become worn out; it can be kept busy always and does not require any special maintenance! Yet there is also another material or instrument that does not rust with time or become worn out with our (- person saving it) use or needs no maintenance at all: it is the money that we have with us!