Building a business is a marathon, not a sprint. Anybody can show up to a meeting with a big smile and a flashy pitch deck, but true passion and will-power ultimately carry founders through the inevitable dark periods, aptly named by Ben Horowitz as The Struggle.

For aspiring young founders looking to start a company from their dorm room, the question remains, where does one find a problem worth solving?

Below are lessons learned from young entrepreneurs who encountered real problems and took them personally enough to build solutions themselves.

Personal challenges can represent real market opportunities

Many entrepreneurs empathize with people in their life who are facing challenges and decide to step up and address the problem head-on.

While pursuing her degree in biomedical engineering, Colleen Costello witnessed her grandmother contract an infection in a hospital. She witnessed a very large problem firsthand: the number one patient killer in the US is hospital-acquired infections. Inspired to eliminate this epidemic, Colleen started Vital Vio, a company that uses LED light to subdue the growth and transmission of germs in places like hospitals.

Similarly, Daniel Fine had already earned his stripes building Glass-U, and decided to next apply his skills to the healthcare sector to solve a problem that hit close to home. His brother, Jake, was diagnosed with Type-1 Juvenile Diabetes at age 7. Now, Daniel and Jake are co-founders of Dosed, a company that enables people with diabetes to manage, track, and determine their appropriate insulin dosage based on their daily diet.

Minor frustrations can lead to big ideas

Not every idea starts with ambitions to save the world. Rather, many businesses begin by addressing frustrations that people face in their daily lives. When these problems are shared by millions of people, solving them can create a big impact.

Dmitry Aksenov and Mikhail Naumov realized that customer service agents make mistakes--it's human nature. For Fortune 500 companies, small mistakes can lead to frustrated customers and damaged brands. To solve this problem, they started DigitalGenius, which provides an artificial intelligence platform that can fully automate human-like conversations with customers while maintaining a brand's identity and personal touch.

The team at Colatris grew frustrated with how slow and expensive it is to localize mobile apps for international markets. They think that teams should be focusing on building products, not managing translations, so they built a plug-in that instantly translates apps into multiple languages--now you can launch globally from day one.

Look inward

There are some concepts in life that simply captivate us, pulling our attention and curiosity like a magnet.

After a power-outage in his hometown in Nigeria, Raheem Bello looked up at the stars in wonder. Simply put, space astonished and inspired him, and he decided to pursue a life goal: be the first person on Mars. While this sounds immensely ambitious, Raheem found his "True North"--a pursuit that would guide his entrepreneurial journey.

Now, pursuing his PHD in aerospace, aeronautical, and astronautical engineering at the University of Texas at Arlington, Raheem is a co-founder of Afthon. The company is increasing the efficiency of combustion engines by leveraging a supersonic combustion process. He's starting by developing solar generators, but ultimately has his sights set on powering something even bigger: a rocket ship.

Take some time to reflect on the people and ideas that matter to you, and stay aware of problems humans face every day, big or small. I hope it helps you find the spark that inspires you to take the leap and build a business that ignites your curiosity for the next decade.

Thank you Thomas Hague for your contributions to this article, and to the Kairos 50 for your constant inspiration.