Want to succeed in sales for a long time and keep your sanity? Learning how to be Zen isn’t just a good idea. It’s a necessity.

Zen, adjective: Relaxed and not worrying about things that you cannot change -- Cambridge English Dictionary

Being in sales means facing regular disappointment, frustration and insecurity. The stress can be overwhelming. Rise above it by taking on a new perspective. I learned how to be more Zen as a door-to-door salesman, and I've carried it throughout my career in all forms of sales and sales management. I live by it.

Stay in the present.

Imagine you'll be in sales for 20 years. That gives you the potential for 240 months without knowing whether you'll be able to cover your bills. How are you supposed to plan your future? You'll turn into a human wreck if you let yourself get caught up in the uncertainty. Instead, learn to stay in the present and focus firmly on the moment. The key is creating your activity-based sales strategy that outlines a set of action metrics to follow every day. You always know your next task, so you can stop fixating on the results and concentrate on the process.

In door-to-door sales, I learned to jump-start my Zen mentality each day by adding a step to my morning routine. At 7:59 a.m., I knocked on the door of any house I was near, even outside my designated sales territory. I didn’t have time to worry or let my mind wander. No matter the outcome, I was dedicated to the job at hand.

Be a human billboard.

Most people will reject what you’re offering. Some will do so vociferously. I’ve been told to “[expletive] off” more times than I can count. I learned to leave my ego out of the sales process, and it was far easier said than done. I decided to see myself as a human billboard. I told myself that when prospects first saw me, they were “reading” what I had to say. After all, some people like and even want what they see advertised on billboards. Most don’t. And that's OK.

I try to be the nicest, most sincere billboard I can be. But my own needs and life stay totally separate. I allow myself to enter into the dynamic as myself again -- all senses fully engaged -- only when someone wants to learn more. They deserve my best, and I give it to them.

Let your successes resonate.

Even when a prospect wants to learn more, it often doesn't lead to a sale. Achieving a state of relaxation in your work requires that you give appropriate weight to your many successes along the way.

The ultimate success might be closing the deal. But success also could mean achieving new steps, such as scheduling meetings or sending out proposals. Every time you advance a potential deal from one stage to the next in your pipeline, let that success resonate within you. The simple acknowledgement that you're moving forward can propel you further than you'd anticipated.

Related: How to Reprogram That Self-Deprecating Little Voice in Your Head

Practice body over mind.

Physical awareness keeps your consciousness focused on your body rather than your mind. It can help you avoid slipping into nervousness and stress. You can achieve it by opposite means: getting yourself pumped and letting yourself relax.

When I felt myself getting nervous about knocking on doors, I started running between houses. I looked ridiculous. Still, after finishing at one house, I'd sprint to the next. It worked. I was utterly in tune with my body and my breathing. I didn't have time to feel anxious. You can do the same in an office setting. Run stairs. Do squats. Get your blood pumping and your energy flowing before or between calls. If you're booked solid during the day, make time for stress relief afterward. Some successful salespeople use high-intensity sports to keep them from stewing in thought and emotion.

Physical relaxation can provide a similar effect. Some people achieve this through yoga or meditation -- arts often associated with Zen, a form of Buddhism. Or it could be as simple as taking a hot bath.

Related: 7 Mind-Body Fitness Strategies That Crush Stress

Develop a mantra.

The reality of sales can be draining, and it's easy to fall into negative self-talk. If I'd created a mantra around how I felt in the early days of door-to-door sales, it would've been akin to: “Nobody buys from you, sucker.” A positive mantra doesn't always need to be true. Sometimes I'd say to myself: “Everybody’s buying.” It helped get me psyched up and reminded me of moments when it had happened. Another of my mantras was more realistic: "There are so many different people in the world."

When people speak to you a certain way, you can become convinced you sparked that behavior. In actuality, it might not be about you at all; you merely intruded in their day. Remind yourself that people respond because of who they are and not necessarily because you've done anything wrong. Of course, assessing and improving your techniques is a necessary part of activity-based selling. But occasional negative interactions simply come with the territory and shouldn’t slow you down.

Feel the mission.

It’s very difficult to be Zen if you feel your work doesn't matter. I've come to understand that I’m a connector. I find people who will benefit from a product or service and show it to them so they can decide if and how they'll let it help them. My personal mission enables me to take pride in what I do and feel deeply good about the entire process, not only its results.

Embrace Zen beyond your work.

Adopting these Zen techniques revolutionized my professional life. But it’s also done so much more. I'm a calmer person, a more present husband and a more understanding father. Learning to be Zen in sales isn’t easy. It takes learning, practicing, failing, forgiving yourself and experimenting to find what works for you. Once you do, you’ll reap big rewards.