For Mohd Oumar Farooq, the key to long-term success lies not in having a groundbreaking idea, but in turning that idea into a business that solves a real problem and can thrive over time.

A recent trade idea lands the Chicago Cubs a two-time World Series champion as an under-the-radar starting pitching addition.

These 10 entrepreneurs launched and grew thriving businesses before the age of 21. Here are their secrets to success.