It's a truth known to every manager: happy employees tend to work harder. Bored employees tend to check out. That's why Gallup's latest "State of the American Workplace" report is such dark news. After interviewing more than 25 million people, researchers found a dismal statistic: over two-thirds of working Americans aren't engaged. 

As Harvard Business Review reported, this disengagement is a troublesome index. Workers who don't care are more likely to jump ship, skip work, or get into safety incidents. If you're worried that some of your employees might be in the 70%, there's a smart solution: incorporating basic psychological theories in the workplace. 

Know the Research

Psychologists are continually publishing new research on efficiency, happiness, and personal autonomy, all of which can be useful to businesses. One area that applies directly to the workplace is self-determination theory, which explains that people want autonomy in their lives--they don't want to be programmable robots or lemmings. Just giving workers the ability to say no enhances positive feelings, diminishing their resentment toward doing what feels like menial labor or grunt work. And skipping criticism to focus on employees' strengths leads to dramatic changes: engagement increases by a third and active disengagement (promoting discord) all but disappears.

One Size Does Not Fit All

HBR writer Susan David encourages managers to use research as a first step, then tailor methods to the specific business. Instead of jumping on criticisms and infrastructure problems, she suggests enhancing the successful aspects of their particular culture. Creating relevant teams and units, both through social events and competitions, can connect employees and make them feel more devoted to success. 

Your business should focus on fostering an environment that understands and respects your specific employees. One company might create a video of top employees, encouraging others to follow in their footsteps; another might focus on a weekly email highlighting the successes and events in various people's lives. That's why it's important to understand both the research and your own employees when trying to boost motivation levels.

Don't Stop Paying Attention

Very little about running a business is static, so don't expect employee motivation to stay exactly the same at all times. Keep an eye on engagement techniques and levels as time goes on, and enjoy watching the productivity increases that happier, more enthusiastic employees can bring.