Do you know how stressed you are? Many people don't, says Michele D'Amico, a certified professional coach with a Ph.D. in psychology. Stress, she explains, comes in three stages, and most people only recognize the first of them in themselves or in their employees.

"Everybody knows the alarm stage of stress, that fight-or-flight, where cortisol starts pumping and epinephrine [also called adrenaline]." The alarm stage doesn't usually last that long, she says. But often people who are under stress then transition to the resistance stage.

"When they're in the resistance stage, it's usually marked by frustration and irritability. Now we have poor concentration where, in the alarm stage, we're very focused." If you're in the resistance stage, she adds, you might experience headaches or digestive issues. That's the time to take action and do something to counter that stress. "If we don't we stay in that stage too long, when we're not pumping as much cortisol, and we become exhausted."

Exhaustion is the third stage of stress, when your energy feels depleted, she says. "If we get to that exhaustion stage, that's where we really get in trouble." At the exhaustion stage, people start having stress-related illnesses, such as high blood pressure, diabetes, stroke, and heart disease, she says. "So we really want to avoid that."

But if the resistance and exhaustion stages are easy for people to miss, how can we even tell how stressed we are? Fortunately there's a simple tool to answer this question called the Perceived Stress Scale. Developed by Carnegie Mellon psychology professor Sheldon Cohen, the PSS has been shown in studies to predict difficulty quitting smoking, difficulty controlling blood sugar in diabetics, a greater likelihood for stressful life events to bring on depression symptoms, and more frequent colds.

The PSS is made up of just 10 questions, so completing and scoring it takes only a couple of minutes. You can take it as an online self-test here, or find it as a PDF here. D'Amico recommends it to her clients who may not be fully aware of how stressed they are, and if you're even wondering if you're in one of the stages of stress, taking it is a really good idea.

Here are a few sample questions, adapted from the PSS, to give you a general idea of the test.

In the last month, how often have you been upset because of something that happened unexpectedly?

In the last month, how often have you found that you could not cope with all the things you had to do?

In the last month, how often have you felt confident in your ability to handle your personal problems?

It's worth noting that the PSS is a perceived stress test -- it measures how you feel about what's going on in your life rather than what's actually happening. That's by design, because stress is an area where perception equals reality. If you think something is stressing you out, then it is stressing you out.

What should you do if your PSS assessment tells you you're having moderate or even severe stress? 

1. Try meditation, yoga, or a workout.

These are three tools people commonly use to combat stress and all three are effective, D'Amico says. In fact, she recommends developing these practices for yourself before you need them. "You want to develop good coping skills for all these stages before it happens," she says.

2. Practice Box Breathing.

Box breathing, developed by Navy SEAL Mark Divine, is a surprisingly simple breathing technique that consists of breathing in for a count of four, holding your breath for a count of four, breathing out for a count of four and pausing with your lungs empty for a count of four. (Here are complete instructions for box breathing.) 

Box breathing is particularly useful, D'Amico says, because it will help you at every stage of stress, including the fight-or-flight stage. Ideally, you would do it for four or five minutes, but "If you can do it just three times, that actually has been shown to lower blood pressure," she says. "I tell my clients to do that before you walk into that meeting or while you're having your tea in the morning before the kids get up."

3. Step away.

"It's that simple," D'Amico says. "Give yourself permission to step away and be OK with that. Maybe it's just being outdoors for a walk. Whatever it is, developing those kinds of coping skills along the way will be very beneficial at every stage of stress."