Principal Financial Group Inc. today announced a "10% Challenge" to retirement plan participants and a new way to track progress through a new retirement wellness report. The report offers a personalized look at current retirement savings and estimated monthly retirement income. The 10% Challenge, said Jerry Patterson, senior vice president for retirement and investor services, will reward participants for saving 10 percent of their income toward retirement. Challenge participants are eligible to win a Fitbit Force, a wristband that tracks daily activity such as steps taken and calories burned. It's part of a renewed effort by the company to help educate people on retirement planning, Patterson said, as studies show many Americans are not adequately preparing for retirement.