By far your most important customer is the customer you already have. Retaining your existing customers must always be your top priority. Satisfied customers come back, and are profitable in the long term. But however loyal your customers are, the day will come when they move away or stop driving a car.
In just the same way as you must always plan your workload for the next few days and weeks, you also need to be constantly recruiting new customers. Then the worst thing that can happen is that you’ll have to expand your business!
This is why you must constantly work to acquire new customers, but not at the expense of your existing ones.