Alison Stevens hasn't taken a real break in 18 months. She says this over the phone during what's supposed to be the first day of a week-long family vacation. First, she has to take our interview, and then she has a few meetings to wrap up with her team. Then Stevens, 51, who admits she's "terrible" at taking time off, will try to unplug while reading a book on the beaches of Cape Cod — as long as there's no cellphone service to distract her.

As the director of HR services at Paychex, a payroll services company, Stevens leads a team of over 600 HR professionals who support small businesses.