Stroll around the office or neighborhood six times a day and earn $1.50 toward your health insurance. Step up activity a bit more and bring the total to $1,400 annually. The catch is that you need to wear a special activity tracker that monitors steps, "intensity" levels and other physical indicators.That is the offer in a new insurance product marketed by UnitedHealthcare, the second-largest U.S. health insurer, one of many programs aimed at boosting physical fitness and reducing health insurance costs for employers and employees."One of the greatest challenges we have is how to incentivize and motivate individuals to be accountable for their own heath and well-being," Steve Beecy of UnitedHealthcare said.He called the Trio Tracker device, introduced with technology partner Qualcomm, "a game-changer."Across the U.S., employers are stepping up the use of technology in "wellness" programs that encourage healthier lifestyles. Wellness programs are not new, but technology like activity trackers has transformed them with more precise measurements and automated uploads to verify activity.A survey of more than 200 large employers by the National Business Group on Health found 37 percent used activity trackers in 2015 and another 37 percent planned to adopt the technology in coming years.Makers of activity trackers such as Fitbit and Jawbone have been expanding their efforts to be part of corporate wellness programs.One of the biggest tie-ups was announced last year when U.S. retail giant Target said it would offer free or discounted Fitbit trackers to its more than 300,000 employees.This strategy of providing financial incentives for healthy activity is known in the industry as "gamification." Jimmy Fleming of the consulting group Healthy Wage said financial incentives can make a difference in spurring healthier behaviors.But the new programs raise questions about private data collected and stored by insurers.While employers and insurers must comply with U.S. privacy regulations so that health data cannot be seen or used by employers, critics still worry."Technology is outpacing the legal protections in place," said Bradley Shear, a Washington lawyer specializing in privacy.Also, some employees will feel compelled to participate because they cannot afford the financial penalties if they do not.Sales of wearable tech devices surged nearly 200 percent in the third quarter of last year to 21 million units, according to the latest International Data Corporation (IDC) survey.