For this hungry entrepreneur, cooking up a business plan meant putting school on the back burner.

Greg Grossman, a 22-year-old chef, restaurateur and co-founder of Kettlebell Kitchen, started the custom meal-plan delivery service tailored to fitness plans and weight-loss goals with more than 25,000 followers on social media when he was just a senior in high school, later dropping out of college at New York University to pursue the business full-time.

“I ultimately decided that this was really what I needed to pour my effort into,” Grossman, who has been cooking professionally since he was 13, told Moneyish. “For me, doing it firsthand was arguably the best experience, and I couldn’t have paid any amount of money in the world for it. No classroom can prepare you for being an entrepreneur.”

Grossman cut his teeth working as a sous chef at the Chicago three-Michelin-star restaurant Alinea at age 13. At 21, he became executive chef and owner of his own restaurant, Oreya, in Southampton. In between, he consulted for several businesses and got plenty of on-the-job restaurant experience working in New York City kitchens, learning from industry mentors.

Then in 2013, Grossman teamed up with army vets and brothers Andy Lopez-Gallego and Joe Lopez-Gallego, who became his business partners. “We launched Kettlebell Kitchens together — and four years later and 50,000 meals a week, it’s a different animal than it once was,” Grossman said.

A prepared meal from Kettlebell Kitchen.

Kettlebell Kitchen was conceived as an aspirational fitness brand for people to customize what they eat based on their goals, whether they be training for a 5k, losing weight or doing CrossFit. Kettlebell lets you plug in your weight, height and fitness objective — muscle gain or fat loss, for example — then sends you ready-to-eat meals, like pesto eggs florentine or grass-fed steak and turkey burgers, each starting between $8.95 and $11.95.

“Meal plans historically have had a negative connotation, because it’s implying that you’re trying to correct something that you were doing wrong,” Grossman said. “Weight Watchers implies that you had a weight issue; Nutrisystem for similar reasons — whereas we tried to position the brand as food offerings with customization as a way of showing that you care about what you’re consuming and ultimately working towards a goal, and not just eating to eat.”

Kettlebell Kitchen started as an online meal-ordering service with the option to pick up Paleo-focused, protein-packed food, specifically in CrossFit gyms. The company launched in New York and over the past four years has expanded to 700 gym locations across Chicago, Boston and down to Philadelphia, also offering delivery nationwide.

“The internet space is now overpopulating. Everyone is battling for the same consumer. Having a refrigerator in gyms, to meet the customers and create a sense of community, has been crucial to our success,” Grossman said. “We want to be the aspirational brand in the nutrition and customized nutrition space. We’re really trying to take personalized nutrition and provide a tangible element as opposed to just getting recipe guides, or having to cook yourself. This is a sustainable option to really help you with whatever your goal is.”

And he’s entered a profitable industry. The healthy meal-kit delivery business is worth an estimated $1.5 billion, according to market research publisher Packaged Facts, and the industry is projected to increase to a multi-billion-dollar market in the next five years.

When it comes to building a sustainable and successful brand and scaling it, Grossman said the key is having a simple concept that’s affordable for the masses.

“It’s about providing a real solution for a need where there’s a lot of demand,” he said. “Everyone wants to be healthier with assistance in improving their well-being, so for us, that was the niche.”