Sometimes being an entrepreneur isn’t just about business, it's about changing the world for the better. Armed with creativity, ingenuity, and persistence, entrepreneurs are uniquely equipped to come up with ideas that can have global impact--ideas that make money. But how do you come up with a game-changing idea of your own?

These three entrepreneurs are tackling some of the world’s most pressing problems, and they’ve turned problem-solving into successful business models. Here’s how they came up with their revolutionary ideas.

1. Pashon Murray of Detroit Dirt

You might be familiar with Pashon Murray from the Ford commercial that propelled her to the spotlight in 2014. Her company, Detroit Dirt, is a composting company that’s turning Detroit’s empty land into urban farms and they’re changing the way waste management and food distribution work in the Motor City. By keeping waste out of landfills and turning it into rich soil for growing food, they’ve become a sustainability pioneer.

So where did the idea for Detroit Dirt originate? Murray drew on what she knew. She grew up helping out at her father’s waste removal business. When she moved to Detroit, she saw a city that needed help--but also a city that welcomed new ideas and opportunity. Detroit Dirt was born out of a combination of knowledge and opportunity. So when you’re looking for your next opportunity, turn to what you know and look to the needs of the community around you.

Finally, Murray’s got great advice for aspiring entrepreneurs: think of your entrepreneurial drive as a mission. She says: "The purpose of your entrepreneurial spirit has to create a solution. Everyday that you wake up you must commit to your entrepreneurial assignment and goals. They never go away, must keep inventing and creating until you reach a plateau and then you’ll create and reach the next plateau."

2. Darnisha Grant Harrison of Ennaid Therapeutics

Mosquito-born illnesses are one of the most dangerous threats to life in the developing world--and where there’s a need for intervention, there’s an opportunity. Ennaid Therapeutics is developing new technology to cure Dengue Fever, West Nile Virus, Hepatitis C, and other illnesses, many of which currently have no known cure.

Founder Darnisha Grant Harrison had 13 years of experience in the pharmaceutical industry when she struck out on her own. But she credits her childhood fascination with science for giving her the push to pursue her ambitious goal of curing some of the world’s most virulent illnesses. "As a kid, I had a love for the complexities of science, and all of those things that were hard questions to answer," she says.

So when you’re searching for your next big idea, think about what your passions are, and what kinds of challenges motivate and move you.

3. Ajaita Shah of Frontier Markets

How do you increase access to energy in poor, rural communities, and keep it green at the same time? That’s the puzzle that Ajaita Shah has cracked with Frontier Markets. In India, over 70% of rural households lack access to regular, basic electricity, and Shah saw that situation as a challenge and an opportunity. Her company markets affordable, quality solar energy products, everything from rooftop panels to lanterns, to households that otherwise have limited access to electricity.

Part of her inspiration, though, came from witnessing a tragedy. Sadly, she saw a child die in a fire caused by a kerosene lamp, which moved her to search for safer energy alternatives. While spreading the solar energy gospel has been hard work, "What keeps you going," Shah says, "is the people."

So if you’re looking for a world-changing idea, look to the people around you: the best business idea might be one that fills their needs.