The lack of relevance came through in the responses to two options: "I'm doing what I need to be healthy," and "The incentive wasn't meaningful."

But convenience wasn't far behind. If one includes the need for more effective reminders in the convenience category, the single category rang up 45 percent of non-engagers.

Let's take a look at the categories and the responses.

Already making good choices: 36 percent

By far the largest portion of the disengaged said they didn't view the wellness plan as necessary to them because they were already following a healthy lifestyle. For a plan designer, this is crushing news. More than a third of your employees don't think the plan has any meaning for a healthy person? If you don't go back to the drawing board to address this, you are offering a failed benefit.

The incentive wasn't meaningful to me: 24 percent

These folks may not be rejecting the entire wellness program. But, like those in the "good choices" group, they're telling you your incentives menu is flawed. Take a look at it. If it's too skewed toward weight management, smoking cessation and managing chronic diseases, you're probably not doing anything to improve the physical, emotional and mental well-being of more than half of your workforce.

Achieving an incentive wasn't inconvenient: 23 percent

Does your plan limit when and where employees can work toward a plan goal? Find ways to open up engagement: Break times just for plan incentives. Once-a-week incentive conversion lunches, with the food brought in at company expense. Mobile access to working toward those incentives will encourage folks to do so on their time, not the time you established for it.

I needed more/better reminders: 22 percent

It's a busy world out there, with generational distinctions, new workplace flexibility models emerging and conflicting demands on everyone's time. Think about how people conduct their days. They use a combination of calendar, text messages, phone calls … all available to them digitally. Adapt by asking workers how they want to be reminded, then make it happen.

Concerns about data security/confidentiality: 12 percent 

Despite management's best assurances, a certain portion of the workforce will always be reluctant to offer up any personal data they aren't legally required to. This group may represent those who will be the most difficult to engage, despite plan design changes. However, gamification could make a dent in these numbers. After all, if something looks like it might be more fun than "dangerous" or "intrusive," people will tend to give it a try.