What is it? Why is it important, and how do you do it? Hang on, here we go. To a dentist, it's brushing your teeth. To a musician, it's practicing. To an athlete, it's training. To a doctor, it's inoculations. For a warrior, it's war games. To an actor, it's rehearsing. And, to the owner of any piece of machinery, it's preventive maintenance.
It is accepting the fact that Murphy's Law exists. Anything that can go wrong will go wrong at the worst possible moment. Once that is accepted, the wise person makes a pre-emptive strike to control the damage done when the stuff hits the fan. Not if, but WHEN it hits.
An old TV commercial showed a mechanic holding a car part and saying, "Pay me now or pay me later." That was a polite way of saying that you were going to pay eventually, whether you accepted that fact or not. Truer words were never spoken.
The hardest part is to accept the fact that maintenance expenses are a certainty. Cars have three costs: their purchase price; their operating costs (gas); and their maintenance costs. Wise operators of commercial vehicles -from busses to semi trucks to ferry boats- realize that breakdowns will happen. If they happen while on the job, a large loss ensues, from outraged passengers to spoiled frozen food, so they routinely replace the parts most likely to fail, before they fail.
That's where the recreational user usually drops the ball. We can't make ourselves spend money to replace parts that are still working. If we will only admit that they are going to fail, we have licked half the problem. We then can look at the amount of money lost by changing it early, and compare that amount to the amount lost from a breakdown, which might include towing and missed appointments.
The best example of believers is the airline industry. They find it difficult to stop and change a tire in the air, and towing is really tricky. Changing it early is cheaper. Hoping the parts won't fail is futile. Some parts are designed to wear out. That is not a communist plot; it is an engineering axiom. Whenever two parts must rub together, one of them is made of a softer material than the other, so that it will wear and the other will not (as much). Then the softer material is changed and you're in business again. An example of softer material is brake lining, clutch lining, rubber belts and tires, and the engine oil and bearing grease. These items are designed to wear in order to protect other parts, and these things must be changed, either now or later. Your choice, like the man said.
Once these expenses are accepted as inevitable, the wise manager sets up a maintenance account, either on paper or in his or her head, and plans to spend those funds intelligently by avoiding loss-of-use breakdowns. Every vehicle comes with a manual which lists recommended intervals to replace these high wear items, and a prudent owner will either pay attention, or pay later, like the man said.
I think his name was Murphy.