Within just three months, Avi Yashchin went from helping manage a $42 billion Lehman Brothers portfolio to working out of a makeshift office wedged between two of his four roommates’ beds. After the Lehman Brothers collapse left him jobless in 2008, Yashchin started CleanEdison, a New York-based job-training company that focuses on the green-building industry. It was a move that forced him to revamp his approach to business. “You always have someone else to do things for you in a big corporation,” he says. “The pendulum really quickly [swung] the other way.”

To avoid running into his roommate’s girlfriend in her towel, Yashchin interviewed potential hires at the Starbucks across the street from his apartment. He became a pro at assembling furniture and replaced the legal counsel he’d had at his beck and call at Lehman with a $200 database of legal documents. “We did everything on a shoestring,” he says. But over three years, Yashchin grew his revenue to more than $3.5 million last year and hired 22 full-time employees. » Read more: How to Make the Move From Big-Business Employee to Small-Business Owner