New York City-based Charles Boyce, 49, spent two decades repressing his inner inventor, until his comfortable life crumbled around him. Then he chased his childhood dream.

--As told to Kate Rockwood

When I was 10, my grandpa took me to New York City. I was fascinated by the trains. I felt destined to invent things for the railroad.

After 20 years running an engineering company, I accepted a buyout from my partner. I went on vacation with my wife to Mexico, and I decided to invest in a vertical milling machine. Who buys a $100,000 machine and hopes to make something people will buy?

Then the bottom fell out of that buyout deal. I couldn't get work because of the noncompete terms, and the legal fees drained my bank account.

I was about to throw in the towel when I got a call asking if I wanted to compete against 11 other companies, including Siemens, for a chance to build an emergency communications system for New York City's transit system in case of a bombing or a health crisis. I couldn't believe it.

I started working around the clock. Before the presentation, I pulled an all-nighter. On the way there, I drove off the road at one point. But when I arrived, the chairman of the subway system pressed the button and it sounded loudly and clearly. That moment was pure joy.

I won. I built 25 units, then 500 more. Now there isn't a day that goes by that I don't build something for a train.