The start-up world has never been so crowded. Launching a tech start-up is cheaper than ever, and jobs at traditional companies, especially for new graduates, are tough to find.

Whether you recently founded a new start-up, or if you're just considering working for an existing one, it is important to understand both the huge challenges and the exciting rewards that lie ahead. I still have decades of knowledge left to gain, but my experiences founding my first two companies have exposed me to great lessons that I use every day.

Here are three pieces of advice that have helped me to get out of my comfort zone and build excellent teams, products and companies:

1. Solve a new, difficult problem.

Naval Ravikant, founder of AngelList and Venture Hacks, a site with tools for start-ups, implores founders of new tech start-ups to change the way they think about product development. Don't just build the next mobile or social app because you've seen a lot of investments there recently. Assess the strengths of your team, and find a market that matches your unique talents and experiences.

One of the reasons why LabDoor generated excitement from early users and investors is that it requires a very specific set of skills to execute effectively. It would have been impossible to build the product data and algorithms needed to grade the quality of pharmaceuticals, supplements, and cosmetics if I hadn't spent years running a FDA-registered product-safety lab first.

Ever since Facebook bought Instagram for $1 billion, many companies have started trying to raise money for new photo and video apps. But simply chasing the last place someone made a billion dollars is a terrible way to innovate.

2. If you want to be Seabiscuit, you better put in a Seabiscuit-level effort.

This insightful piece of advice comes from a source with zero business experience--my high school football coach. Anyone who has met me in person knows that I look nothing like a football player. But my effort to compete in a sport I wasn't built for led me to some of my best entrepreneurial lessons. The star linebacker can take a play off, but I had to push myself every day, in every after-hours practice session.

I still operate that way. Find the parts of your business that you weren't built for, and work like crazy to improve.

3. Squeeze yourself into uncomfortable situations--and then work your way out.

Scott Case and his Startup America network provide a never-ending stream of excellent business advice. One of his best lessons helped me in my transition from a running a scientific lab to building a tech start-up. It's easy to get comfortable in a small business. Core products and services have been defined. You have a team of employees who listen to you. The sales team has happy repeat customers to rely on.

Force yourself to break out of daily tasks and habits. Learn to code, and start building your passion project. Find the last seat at a full table of strangers during the next networking event. Volunteer to teach a course at your local business school in a subject you've always struggled with. Explain the new mobile app you're building to your low-tech father-in-law. Challenge yourself every day, and you'll become a better entrepreneur.

Neil Thanedar, 24, is Founder and CEO of LabDoor, a mobile health start-up providing report cards for pharmaceuticals, supplements, and cosmetics. @NeilThanedar