Bob Keller's three reasons for continuing to work are representative of many Baby Boomers: "First, I can't afford to retire. Second, I'm happier and saner when I'm busy. And third, my wife would never stand for it."

Keller, an illustrator and graphic designer, took his pension in 2009 at age 59 1/2 when his company declared bankruptcy. If he hadn't "retired" by the end of that year, his pension would have been in jeopardy.

Still, he said, "I never thought about kicking back to go fishing."

While his current business is "60 percent print, general design and brochures," he's added a sideline building and hosting Wordpress blog sites.

He said he's "trying to get busier," but he's already cut the monthly draw on his pension by nearly two-thirds and can imagine giving up the Social Security benefits he claimed when he turned 62.

"The overhead is so minimal for what I do, and you can do it from anywhere. I'll probably keep working as long as I can," Keller said. "I don't have a succession plan -- what would my clients do if I retired?"