Positive attitude means conveying optimism, generosity, support, and enthusiasm in your expressions, gestures, words, and tone.

There is no doubt employee attitudes affect productivity, quality of work, and morale; collegiality, cooperation, and cohesion; and employee development and retention. Good employee attitudes drive positive results. Bad employee attitudes put a drag on results. That’s a fact proven by study after study, including our own.

Even if you could get inside your employees’ heads, you shouldn’t try. It is not your job to be your employees’ therapist. What you must do instead is focus on the external behavior: What you can encourage them to do is learn to keep their negative feelings to themselves and smile on the outside more at work.

Do not make the three most common mistakes that many managers make when dealing with bad attitudes:

• treating attitude as a personal issue, an internal state of mind that is off limits 

• treating attitude as an unchangeable matter of personality (“that’s just who I am”) 

• talking about attitude in vague terms or indirectly.

As long as you think of attitude as a personal, internal matter, it is going to remain intangible and you will remain out of your depth. Feelings are on the inside. Observable behavior is on the outside. Attitude is just the translation of feelings into behavior. No matter how intrinsic the source may be, it is only the external behavior that can and must be managed. As a leader, dealing with attitude becomes a whole lot easier if you treat it head-on, directly, as just another matter of performance management.

Here’s my best advice:

• Make great attitude an explicit and regularly discussed performance requirement for everyone.

• Make it about external behaviors, which employees can modify as necessary.

• Define the behaviors of great attitude: expressions, words, tone, and gestures. Describe the behaviors. Require them. Teach them. Reward people for displaying them proudly. Hold people accountable when they don’t.

This is the message I recommend managers deliver when they are trying to convince their employees to commit time and energy to developing a good attitude:

Attitude may be hard to define and describe. But it is very, very important. At every level, leaders and managers rate attitude as one of the most important factors in employee performance. Attitude can be the difference between success and failure for our business. Attitude can be the difference between success and failure for any employee.

Here’s some good news: Research shows that if you make an effort to display positive words, tones, and gestures on the outside, it has a positive effect on your internal brain chemistry and it actually makes you feel better on the inside. Good attitudes can be a self-fulfilling prophesy: Behave as if you feel positive, and you will eventually begin to genuinely feel positive—and experience positive results.