For too long, employees have seized on multi-tasking as a way to be more efficient and effective at work. But experts like Andy Lee believe multi-tasking can actually hurt your performance. Attempting to do several things at once "fractures your attention, stresses you out, or just burns your mental energy," Lee says. "It also kills your creativity and leads you to make more mistakes."

The real way to enhance effectiveness, he advises, is being “mindful”: "If you try to do one thing at a time, you're going to be way ahead of the game." Lee should know: As Aetna's chief mindfulness officer, it's his job to promote mindfulness programs for Aetna employees and members. But what is mindfulness, exactly?

"Mindfulness is about paying attention to the present moment with an attitude of openness and curiosity," Lee explains. "We go through the day with a lot of expectations, judgments, preferences and biases that we bring to situations before we're even in them. Mindfulness is about noticing what's actually going on before we start making up our minds."

Watch our Glitter Jar animation, which demonstrates the power of mindfulness for all ages.

Lee, as you might expect, practices mindfulness. But you'll find executives at other businesses who are dedicated to it, too. Here's what Lee and three other company leaders — Hannah Grove, of financial services giant State Street Corporation; Jay Shapiro, of the do-it-yourself app firm AppMakr; and Katharine Zaleski, of PowerToFly, a recruiting platform that matches employers with highly skilled women — had to say about why mindfulness is important to them.

Andy Lee, chief mindfulness officer, Aetna

What first interested you in mindfulness?
About 20 years ago, an executive coach asked me if I ever thought of meditating. I think what he saw in me was someone who was kind of stressed out, going too fast, and impatient. I started to do it and I saw the benefits. It's really been helpful for me throughout the ups and downs of my professional and private life. Now I feel like I know what I'm doing and why I'm doing it. The big things don't stress me out as much as they used to.

How do you practice mindfulness apart from meditation?
In my work group, we usually start every meeting with a minute of mindfulness practice: sitting quietly and paying attention to the breath. We also promote this practice across the company — taking a mindful minute. It’s amazing how just 60 seconds of silence can calm and refresh the mind.

When I'm at my desk, I also make sure to get up at least every 90 minutes and walk around. Stretching and engaging your body can help switch the channel in your brain. And I pay attention to the stories I tell myself — I try not to get caught in mental loops, like going over a past situation again and again.

Basically, the more often I can check in with myself during the day about what I’m doing and why, the better my days go.

Read more tips on staying focused at your desk.

Hannah Grove, chief marketing officer, State Street Corporation

How do you prioritize mindfulness?
I start my day meditating at home three or four times a week. And then, no matter how busy the day at work, I always take 15 minutes to walk around, preferably outside, just to recalibrate and not get too consumed with the deluge of the day. I also walk to and from work irrespective of Boston’s charming weather conditions and use that time to think.

Why is mindfulness important to you?
There are three reasons. It forces me to step away from all of the chatter and noise in any given day and refocus my mind, which in turn helps me to think more clearly. Second, it helps with stress because it makes you breathe. I have a sneaking suspicion that we’re all oxygen deprived from holding our breath throughout a hectic day. Lastly, I think, but can’t prove, that it makes me more creative because my mind isn’t just processing tasks or a to-do list.

Jay Shapiro, CEO, AppMakr

How does being mindful help you run your company?
As a CEO, mindfulness is incredibly important. The difference between a "manager" and a "visionary leader" lies entirely in your clarity of thought, contagious enthusiasm and articulateness. In the face of a thousand varied challenges a day, the ability to mentally juggle them and maintain a positive attitude requires a healthy mind and soul. Like any other part of the body, they need intentional care and exercise to stay at peak performance.

How do you practice it?
I have two routines that admittedly are unusually technologically grounded, which is not what you would expect from the mindfulness crowd. The first is meditation using a mobile app called Calm. (Full disclosure: I liked the app so much I invested in the company.) The app provides me with a rapid and guided journey at difficult points in my day. This helps to re-center my thoughts, increase focus, and oftentimes opens my mind to innovative solutions.

The second entails visually organizing information. I'm a compulsive mind mapper and I use tools like MindJet and Trello, which allow me to take the buzzing swarm of thoughts flying around in my brain and organize them into some sort of cohesive symphony, with each thread of ideas, concerns, and to-do's fitting into a context and priority. This greatly reduces any stress and anxiety and allows me to maintain that positive outlook that team members absolutely sense and feed off.

Katharine Zaleski, co-founder and president, PowerToFly

Why do you value mindfulness?
Mindfulness is key to my role as the cofounder and president of a gender diversity platform for top brands. Every company presents us with a new challenge. So if I haven’t cleared my head each morning through my mindfulness routine, it’s very easy to get stuck and not see a clear path forward.  And as a manager, it’s also important for me to take ten minutes each morning to remind myself of my intentions for the day.

How do you incorporate mindfulness into your day?
I meditate each morning for at least 10 minutes. I include it in my daily routine, much like I brush my teeth or wash my face. I use the Headspace app and also write in a journal to remind myself that, yes, I’m solving problems every day, and they’re compelling and impactful problems that I’m lucky to have the opportunity to tackle. Writing, along with guided meditation, sets me up to be a focused and empathetic boss who doesn’t jump to conclusions. I listen to my team, but I need to force myself to take time in the morning and remember to listen every day.