I like this chinese idiom: 流水不腐, which means “flowing water does not rot”.
This is a basic phenomenon. If the water can flow, the water sure be clean. This idiom can be applied to many circumstances.
The drain need to be unobstructed, so that the water can flow, and the drain will be clean.
We need to allow the air of the room circulate so that we have enough oxygen.
We need to go to toilet, so that the our organs will be clean, and we will not sick.
For me, this idiom also points out that I need to practice my skills always, so that my skills will not be dull. Just like an old man need to use his brain otherwise he will become dull. We often said that, if we don’t use our brain, our brain will get rusty.
Right, if a machine we don’t use it, it will get rusty. You might also say, the machine will have longer life span if we seldom use it. Since you have the machine, why don’t just use the machine so that the machine becomes useful? Since you have the skill, why you want to waste it?
Besides that, in the spiritual perspective, we need to do spiritual practice frequently so that our spiritual life will not be rotten.