The key to creating a successful business is finding an unmet need and filling it. But sometimes, to quote Steve Jobs, "People don't know what they want until you show it to them."
For example, you probably never realized your dog needed protective eyewear. Then Roni Di Lullo came along and created Doggles — goggles for dogs.
First year sales were $100,000.
Last year's sales were $3 million.
Read More from CNBC: The Most Expensive Dog Breeds to Insure
This is the story of how a software programmer from Hewlett-Packard used her computing skills and love for man's best friend to create a pet product empire. When Di Lullo started, though, people at her first trade show mocked her. "We were sitting down in the booth, and people are just walking by, and they're pointing and laughing, and we're just like, 'Oh, no.'"
Act I: The Frisbee mystery
The story of Doggles began with a walk in the park. "I originally came up with the idea from my border collie, Midknight," said Di Lullo. After a long day at work, she and Midknight would go play Frisbee in the park in the late afternoon. Di Lullo would wear sunglasses to protect her eyes from the brightness of the setting sun. "There was one day in particular where (Midknight) missed the Frisbee, and he never, never missed the Frisbee," she said, "so I just thought, 'Well, why can't he just wear sunglasses, too?'"
That was 1997. Di Lullo spent months trying to adapt sunglasses, ski goggles, and swim googles for her dog, until she realized she was going to have to create a pair from scratch. "I made the designs in a CAD program," she said. Di Lullo invested $25,000 on the concept, and she started producing and selling Doggles more as a hobby than anything else. She had just become a new mother and was taking a leave of absence from work. "I hadn't really thought of it as, 'This is just a product I'm going to sell a ton of. '... It really was for fun, but once I did it, I realized there really was a market for this."
Read More from CNBC: More Firms Allowing Dogs (and Other Pets) in the Office
As for whether dogs find them uncomfortable, Di Lullo said: "It really depends on your dog. Some of them will just very happily walk away wearing them, but the good majority of them need to be trained to wear them.
"Some dogs just won't wear them period, it just depend on your dog's personality."
Act II: The cold call
Then, in 2002, "A few very big things happened then." CNN did a story on the company. Even bigger, Di Lullo decided to cold call the toll-free number at PetSmart. "I just said, 'How do I submit a product?'" She was given an address, and Di Lullo mailed the company a pair of Doggles. "A couple of weeks later I got mail — an actual letter — back saying that they took the product in all of their stores."
Suddenly Di Lullo needed to find a manufacturer. Until then, she had been putting the finished product together herself by hand. "I just started making phone calls," finally settling on a manufacturer in Taiwan.
Doggles provide dogs with UV protection. They are also flexible and shatterproof. Di Lullo said they're popular with motorcyclists whose dogs ride in sidecars, or drivers whose dogs like to stick their faces out windows. Veterinarian ophthalmologists find them useful after canine eye surgery, and they're popular with military and police K-9 units. The only place where Doggles don't work is in the water, because the goggles have holes in the side to keep from fogging up.