Long hours, heavy workloads, tight deadlines, job insecurity, a lack of control over your schedule and generally feeling unsupported can leave you feeling unhappy and discontented with your work environment. If gone unchecked for too long, this kind of chronic workplace stress can lead to job burnout.

As a Harvard-trained psychologist, one of the best ways to cope with these stressors is to set healthy boundaries. It might sound like a tall order. You may worry that you will make yourself seem difficult or unprofessional. But setting healthy boundaries is key to mental health and stress-relief. 

Simply put, boundaries are relationship expectations. 

They establish who you are, what you're willing to do — and not do — as well as how you want to be treated and what you'll do if someone violates those expectations. Boundaries reflect your values as a person. Establishing them helps you feel a sense of belonging, competence, safety, fairness and meaning in your work environment.

DON'T MISS: The ultimate guide to becoming a master communicator and public speaker

Although we don't have the power to change other people or a company's culture on our own, communicating our boundaries promotes a healthier professional environment for all. Here are eight phrases you can use to start setting clear boundaries today. 

1. 'I need more time'

Setting reasonable timelines is helpful for managing stress. When asked to do a task or project that's going to require more time than requested, communicate that as early as possible.

This boundary sets the expectation that you're both willing to do what's required and reasonably need the time it takes to do it well.

2. 'I'm not available'

Establishing when you're on the clock and when you aren't is also key to reducing stress. If you find yourself continuing to check work-related emails or taking calls when you're on vacation or supposed to be "off-duty," this communicates to those around you that you're always available. 

Setting a boundary that there are times that you will be unavailable because other aspects of your life will sometimes take priority, is critical to self-care.

3. 'I need help'

When a task becomes overwhelming or is outside of the scope of what you know how to do, asking for help is reasonable and warranted. It sets the boundary that you need some assistance to do a job well, and that you care enough to ask for it.

4. 'Please speak to me respectfully'

Some work environments can be toxic — negative, unsupportive or downright abusive. But even in healthy environments, stress can make people speak in unintentionally disrespectful ways.

If you find yourself in an emotionally heated situation that's derailing into a tense moment, or even a full-blown argument, it's important to set a boundary around communication itself. Stating that you'd like people to speak to you respectfully or you will walk away, is a healthy boundary to set in any relationship, including with coworkers and colleagues.

5. 'I have a suggestion'

When confronted with a situation that's not going well, one way to set a boundary is to describe your observations and suggest an alternative strategy for handling it. 

In this way, you're communicating that you don't like the way a current situation is being handled while taking a proactive, problem-solving approach about how to handle it in a way that could work better for you.

6. 'I feel underappreciated'

Work-related stress is often elevated when your effort doesn't seem noticed, acknowledged or appreciated. If that's happening to you, it's very reasonable to talk to colleagues or high-ups that you're working hard but feel undervalued. 

This sets an expectation that when you think you're doing a great job, it's important to you to have that acknowledged.

7. 'This doesn't seem fair'

The perception of unfair treatment is a key predictor of work-related stress and burnout. When a policy or experience doesn't seem ethically handled, directly communicating your experience not only makes your perspective of unfairness clear, it also creates a mechanism for change.

8. 'I want to be more engaged'

Work-related engagement is the opposite of burnout. It's being part of a workplace that feels like a good fit for who you are. This includes thinking that your career is meaningful, feeling connected to your colleagues, experiencing positive feelings towards your job and being valued or competent in your work community.

When you don't feel engaged at work, communicating that directly conveys that you want to be a more connected, productive member of your organization or group.

Don't be afraid to set boundaries at work

Establishing boundaries at work can sometimes feel uncomfortable for many people because it can be vulnerable and feel risky. But ultimately, communication is key to developing and maintaining positive work relationships. 

Although we don't have control over other people and how they respond to us, we have control over our own behavior. If a productive conversation doesn't seem possible, walking away and processing your experience with someone who can listen, support you and validate your experience is always a good option.

Dr. Cortney S. Warren, PhD, is a board-certified psychologist and author of "Letting Go of Your Ex." She specializes in love addition and breakups, and received her clinical training at Harvard Medical School. She has written almost 50 peer-reviewed journal articles and delivered more than 75 presentations on the psychology of relationships. Follow her on Instagram @DrCortneyWarren.

Want to be a successful, confident communicator? Take CNBC's new online course Become an Effective Communicator: Master Public Speaking. We'll teach you how to speak clearly and confidently, calm your nerves, what to say and not say, and body language techniques to make a great first impression. Sign up today and use code EARLYBIRD for an introductory discount of 30% off through July 10, 2024.