Gururaj Deshpande's first entrepreneurial venture netted $26.95. The chairman of Sycamore Networks keeps a framed copy of the check as a reminder that finding his passion for building companies was the real payoff.

Deshpande rejected the idea of returning to his life as a professor and software engineer after his first failure. Instead — in the wake of financial ruin — Deshpande would light out in search of his next entrepreneurial adventure, emboldened by a taste of his true calling.

If it's something you really believe in, he asserts, "you don't really [have] look for anybody else to approve of that conviction. ... You're going to make it happen."

And he did. Six months later, Deshpande launched into his next endeavor. Cascade Communications, as the company was called, would be a gamble at manufacturing Internet equipment. His doubters were many, reinforced in their pessimism by an industry dominated by Cisco Systems.

Desphande stayed the course, always keeping true to his vision. Conviction is central to the serial entrepreneur's success, he maintains, because "everybody that you talk to is only going to try to discredit you. They're going to try to tell you that it's probably not something that is going to work."

In 1997, Cascade was sold to Ascend Communications for $3.7 billion. By that time 72 percent of all Internet traffic was coursing through Cascade's products.

Success or failure, it was the doing he loved. So he did it again. "You always have to do, at least in order of magnitude, more and different than what you've done in the past," explains Deshpande.

Sycamore was founded a year after Cascade in anticipation of the optical-networks boom. In a little over two years, Deshpande built the company up to a market valuation of over $23 billion.

With his second multibillion-dollar company, Deshpande has succeeded in making himself one of the richest men in the world. His net worth tops $4 billion. All thanks to an earlier experience worth just $26.95.

Tune into PBS' Nightly Business Report Thursday to see Donald Van de Mark's interview with Gururaj Deshpande. Prime Movers airs every Thursday on the Nightly Business Report. Check your local listing for times.