With all the positives it offers for community, exchange of information, and plain old fun, social media can turn into an instrument of profound harm, fueling poor self-image and depression, and encouraging potentially lethal activities such as the recent "Chroming Challenge" that has killed kids who are huffing toxic fumes.

It turns out that a nifty little track-it-all-and-tell-me-everything device you have on your wrist can turn on you, too.

A study in the Journal of Consumer Affairs looked at how people are engaging with "preventive health technologies" and discovered that the devices are often a double-edged sword.

While they can provide accountability, motivation, and encouragement, they can also lead to stress, anxiety, and feelings of failure from compulsive overuse. That can derail your efforts to become healthier and happier.

What's the formula for the smart use of such monitoring tech?

• Determine what you want to use it for and why. Tracking minutes of exercise or steps a day? Monitoring your blood pressure? Seeing how much sleep you're really getting and what hours? Choose one to three areas that are most important.

• Set targets that are best for your health instead of sticking with preset goals programmed into the device.

• Recognize that you're on a lifelong journey, which will have peaks and valleys; it's not just up, up, up. Give yourself a break on days you miss a mark and start fresh the next day.