Breaking points are subjective. Some people are just hardwired to handle certain stressors better than others. Take ultra-marathoners, for example. They run 100k races while most of us are happy to finish a 10k.

When it comes to work, we all have that co-worker that will put in an extra 20 hours a week like it’s no big deal, while many of us struggle through a regular work week.

Because everyone’s tolerance for stress is different, it can be tough to draw a clear line between rising to a challenge at work, and crossing into the danger zone of being overworked. For example, while your superstar co-worker may have time to put in an extra 20 hours a week, you may have a family at home that requires your attention, and may not be able to handle as many overtime hours without feeling like you’re at your wits’ end.

Though breaking points may be different for everyone, there are certain gauges that can help you establish a personal boundary between stepping up to the plate at work, and stepping into the dangerous territory of being overworked.

Examine the emotional effect

If your workload is affecting your emotional health, chances are, you’re overworked. Employees who worry about not getting work finished and keeping up a fast pace can feel like they are drowning in their workload, a feeling that manifests itself in chronic stress and anxiety.

“[Being] overworked is about the gap between the tasks you are currently doing and what you expected to be doing,” says Louis Barajas, author of “Overworked, Overwhelmed, Underpaid.” “It can also mean that you are working too many hours. When you are asked to do more than you think you should, to do tasks beyond your capabilities or work more hours than your mind and body can take, you can quickly burn out. The stress also creates a lot of tension in personal and work relationships.”

If you find yourself unable to sleep because of work-stress, or if you are feeling so strained that you take it out on the people you love, it’s time to reevaluate your workload.

However, Barajas says, not everyone experiences burnout from working long hours. Those who enjoy the type of work they do, and feel that they are making a worthwhile contribution to society experience less incidences of feeling overworked, and may be able to work longer hours without a negative emotional impact, than those who don’t find satisfaction in their job.

“If you are doing work that has purpose or meaning, you tend to see the work as justified because of the vision of the ‘end in mind.’ For example, when President Barack Obama was running for election, a lot of his volunteers were working almost 100 hours a week.  They had tremendous energy and felt that their time and effort would eventually change the history of America,” he says.

If you’re starting to feel like you are overworked, evaluate whether it’s due to longer hours and increased workload, or whether it’s time to consider other, more fulfilling career options.

Examine the physical effect

One of the key indicators that you’re being overworked and not merely challenged, is if work-related stress begins to take a toll on your physical health.

“Being overworked can manifest into different types of physical symptoms,” Barajas says. “You get sick a lot, your immune system weakens, you can get depressed, you can get insomnia.  All these symptoms can cause more fatigue related errors at work or in your personal life.”

According to the Mayo Clinic, other physical symptoms may include headache, neck pain, lower back pain, depression, changes to appetite and chronic fatigue. If you experience any of these physical symptoms, it’s time to talk to your supervisor about adjusting your workload.

Assess whether the heavy workload is permanent

All jobs have ebbs and flows — periods of heavy workloads, and periods of not-so-heavy workloads. Accountants, for example, may work far more hours during tax season then they do during the rest of the year.  If your job is cyclical, or you are assigned to a high stress project that is temporary, you may have no other option than to rise to the challenge.

“Unfortunately, there are times when you do need to suck it up and do the extra work,” Barajas says.  ”But you should suck it up temporarily. You need to create a plan to move forward and free yourself from the tyranny of work that creates such dysfunction in your life.”

Feeling like your workload is constantly insurmountable and like you can’t seem to get ahead means that you’re at risk for being overworked.

Discuss it with your supervisor

If you’re still unclear as to how serious your work stress is, address the problem with your supervisor. Tell your boss how you are feeling in an objective way, taking care not to come off as “whiny” or like you’re complaining, which will make you seem immature and like less of a team player, especially if the whole office is feeling overworked.

Instead, Barajas advises “Don’t be part of the problem, be part of the solution. If the bosses will listen to you, offer constructive advice as to how you can make the work more efficient and tolerable.”

If your boss is elusive, or doesn’t take your concerns seriously, look into whether your company has an Employee Assistance Program. Oftentimes, such programs offer therapy, counseling and support to employees who are having workplace issues. If your company doesn’t offer an EAP, it may be time to evaluate whether your job is worth the potential risks to your well-being.

For more information on burning out at work, visit the Mayo Clinic website.

Kaitlin Madden is a writer and blogger for CareerBuilder.com and its job blog, The Work Buzz. She researches and writes about job search strategy, career management, hiring trends and workplace issues. Follow @CBForJobSeekers on Twitter.