When Jeffrey Nash, 60, started thinking about his retirement several years ago, he didn't like what he saw. As a salesman for Men's Wearhouse, his income went up and down, and he hadn't yet saved much for retirement. In addition, he was struggling to pay off a mortgage at risk for default.

So Nash decided to build his own business outside of his full-time job in an effort to shore up his finances. He created a new baby walker product he named a "Juppy" and started shopping it around at baby product conventions during his vacation time. His work paid off: Today, he runs his company full-time, and the Juppy has brought in over $200,000 in revenue. Instead of worrying that he'll spend his retirement in poverty, he plans to continue growing and running his business over the next decade and beyond.

Nash is one of thousands of retirees and near-retirees who are becoming entrepreneurs, turning the traditional view of a laid-back retirement on its head. The Kauffman Foundation reports the 55- to 64-year-old age group represents almost one-quarter of new entrepreneurs in 2012, compared to just 14.3 percent in 1996. The cohort also has a higher level of entrepreneurial activity than the 20 to 34 year old group.