A business has to walk a delicate line between serving existing customers and prospecting for new ones. It’s hard enough when you have a big company with distinct departments to handle the unique needs of each.

But when you’re a mom-and-pop operation or a solo entrepreneur, those challenges are magnified. And if you decide you can’t take care of your customers and solicit new ones at the same time, the repercussions for ignoring one of those constituencies are negative.

Choose to serve existing customers only, and you’ll find, one day, you have no fresh pool of people who need your services.

Concentrate on prospecting for new customers at the expense of serving current customers, and you’ll leave a wake of dissatisfied customers whose negative reviews thwart any ability to find new ones.

A neighbor of mine was pleased with her contractor’s remodeling project on her house and referred him to all her friends. A solo operator, he became overwhelmingly busy with all those referrals and eventually stopped answering his phone; he was too busy to bother with new requests.

Friends reported back to my neighbor that they had called this fellow repeatedly with no answer or callback, and they eventually used different contractors.

Fast forward eight months, and this same contractor was knocking on my neighbor’s door, asking for business. He had exhausted his current supply of customers, had no prospects waiting in the wings, and had burned bridges with all those referrals he had ignored.

A professional handyman struggled with this same challenge. As a one-man operation, he couldn’t answer phone calls from prospective customers if he was on a roof or crawling under a house doing work for existing customers. Realizing that he was losing future business, he bartered services with another entrepreneur who could answer phone calls and set appointments for him.

A friend recently was disappointed with a specialty food product whose label touted its family business where love, pride, and quality organic ingredients were the mainstays of their foods. So disappointed that this product did not fulfill expectations, he figured that that particular item had escaped quality controls, so he sent photos and the lot number to help them figure out why this product was missing key ingredients.

The company’s response was that was the way the product was supposed to be, that others liked it, and they guessed that he just didn’t like their product. No explanation why the product didn’t match the package photo or description.

No suggestion to try one of their other products. Just a terse, “others like our product, and we guess you don’t.” In other words, “we have enough customers, thank you, so we don’t need you.”

I am reminded of an old business lesson about a food retailer who did a hefty business in selling fresh fish that was procured daily. A customer told him that he should sell fresh fish, which surprised him.

He explained that their fish was indeed fresh, and their supply came in daily. She didn’t believe him. Now, at this point, many of us would have simply discarded that customers’ arguments as silly — after all, the store already did quite a brisk business in fish, and they didn’t need this one customer buying its fish.

Pressing the issue, he asked why she thought their fish wasn’t fresh, and she replied that “everyone knows fresh fish is on ice, not in plastic wrapped packages.”

Deciding that “enough” customers were not enough, he experimented the next day with putting that day’s catch on ice. Sales skyrocketed.

Every business needs to serve existing clientele while at the same time market for new ones. “Enough customers” today might mean no customers tomorrow.