One sure-shot means to damage a machine is to drive it too hard. Another means that is just as effective, is to not use it at all and let it gather dust.
When you don’t use a car regularly, you still ought to clean it, periodically start it up, rev up the engine and take it for a quick ride. For the automobile to remain usable and trustworthy, the engine needs to be warmed up and the parts need to be lubricated every now and then.
As artists, we know that the wellspring for our best work, the muse, is impulsive and impatient. We serve as her chauffeurs, for we know that when she is riding with us, we do our best work. When the muse shows up around the street corner, the artist ought to be ready and waiting with a car in perfect condition.
Having a regular practice ensures that your engine is warm and well oiled to go at a moments notice. Otherwise, even as you struggle to cold-start your rusty car, the muse promptly moves onto the next person who is waiting for her with a car in perfect condition.