We all have those mornings: You wake up in a panic because the alarm didn’t go off; stub your toe on the corner of the bed while hurrying to the bathroom; cut yourself shaving; burn the toast; hit every red light on the way to work and arrive ten minutes late, thankful it’s just ten, only to realize you left your delicious lunch of leftovers sitting on the kitchen counter. At his point, you probably feel like throwing your desk out the window, not sitting at it for the next eight hours trying to be Mr. Productivity.

But, you soldier on, knowing your paycheck depends on it, and get through the day.

Your colleague, Karen, on the other hand, has a fantastic morning. She wakes up before the alarm, having gone to bed a bit early the night before; has a nice breakfast and scrolls through the Times on her iPad before heading upstairs to get ready. She is out the door at seven on the dot, avoids the heavy rush-hour traffic and walks through the office doors two minutes early, the lyrics from her favorite new song still buzzing in her head.

Karen doesn’t soldier through the day; she glides on top of it, using the morning’s positivity to shape her outlook and interactions.

Now, if you were to present your morning and Karen’s to five strangers and ask which person they thought was more productive that day, who do you think they’d choose? Karen, right? Not only is she the logical choice, she’s also the proven choice. According to a study performed by Dr. Nancy Rothbard of University of Pennsylvania’s Wharton School, in conjunction with Stephanie Wilk from the Fisher College of Business at Ohio State University, employees who started the day in a positive mood tended to remain positive throughout the day and perform better. Conversely, those who started the day in a bad mood often saw their mood worsen throughout the day, accompanied by a 10% decrease in performance.  Makes sense to us.

The upshot: positive moods = better performance, so anything companies and organizations can do to boost employees’ moods at work will improve the bottom line.

If you were to take this conclusion one step further, however, and infer that promoting positive thinking will increase employee and company performance, well, that might be one step too many. Apparently, “at the psychological level, positive thinking—measured by its effect on blood pressure—relaxes us and drains us of motivation.” At least that’s what studies by psychologist Gabriel Oettingen have shown. Whether she studied obese patients trying to lose weight or students in a business skills class trying to get an “A,” those who fantasized about success achieved poorer results than those who did not. The trick, it seems, is to temper positive thinking with a realistic assessment of potential obstacles, a technique Oettingen calls “mental contrasting.” She covers the benefits of this technique and others—such as WOOP (wish, outcome, obstacle, plan)—in Rethinking Positive Thinking, published this month by Penguin Random House.

In summary: keep employees happy but grounded at the same time.  This may be an oversimplification, but at Anderson|Biro, we like to keep things simple.