Then her mom calls and guilt-trips her for forgetting her aunt’s birthday.

Oh, and that new guy she has been texting?

Her stress hormonescortisol and adrenalineare surging.

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Getty

For now, this will hone her recall.

Allsheknows is that she’s overwhelmed.

So at lunch, sheheads to the gymand hops onto the elliptical.

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Meredith Jenks

“BDNF,” Dr. Ratey says, “is like Miracle-Gro for your brain.”

Unlike those deprived mice, Woman A is feeling so good that she cranks up the elliptical.

As she does, her body begins releasing gamma-aminobutyric acid, or GABA, a calming neurotransmitter.

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Meredith Jenks

Not that she is calm, exactly; she’s subjecting her system to a low-level form of stress.

“Exercise raises your heart rate and triggers a surge of hormonal changes.

Expose yourself to this ‘stress’ enough and your body builds up immunity to it.

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Meredith Jenks

Which leads us to Woman B.She is also having a bad morning and feeling overwhelmed.

Except in her hormonally revved-up state (adrenaline!

), she decides she is too time-pressed and anxious to work out.

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Meredith Jenks

Instead, she treats herself to a cookie and a latte.

But her buzz won’t last for long.

By midafternoon, shecrashes and feels more stressed than before.

That may partly explain why depressed and anxious people get locked into a negative mind-set.

Not so, Woman A.

After her workout, she has a sunnier outlook.

Which would you rather be?

We thought so.With those benefits in mind, SELF did an experiment.

The outcome: Let’s just say the women used phrases like “life-changing.”

(And “body-changing"one woman lost 14 pounds!)

The science:“Exercise engages neurons in the brain, just like it engages muscles in the body.

That raises the brain’s stress threshold,” Dr. Ratey says.

“People who exercise regularly don’t respond as dramatically to stress as nonexercisers do.

Their heart rate doesn’t shoot up as high, and their mood doesn’t sink as low.”

Schwerd’s hurdle:“I work long hours at a cancer center and have lots of meetings.

That makes it hard to get to the gym,” Schwerd says.

“I love my work, but it’s intenseI help patients deal with life-and-death issues.

I want to enjoy my job without feeling exhausted by it.”

It was intimidating, but I felt connected to my body for the first time in a long time.

All my energy used to go into my job.

My stress disappears.”

If I had 8 minutes, I’d get on the treadmill for 8 minutes.

The more I exercised, the more in tune I got with myself.

I’m no longer overwhelmed by work, and I fit into clothes that used to be too small.

I’m hooked on the exhilaration of pushing myself physically.”

Being accountable to someone will help her stay motivated."

The science:Exercise is a powerful weapon against the blues.

“In the short term, it can elevate mood when you’re feeling down.

Long term, it can knock out milder forms of clinical depression,” Smits says.

“My cat Squirrel died, and I ate for comfort.

The weight gain made me feel bad about my bodyI was too embarrassed to exercise in front of anyone.

Seeing myself in the mirror at the gym was disheartening.”

Her biggest motivator:“It really helped to have Larysa Didio train me.

I also loved walking with a friend by the Hudson River.

There were tons of people biking or walking their dogs.

I always felt happier afterward.”

From there, I began building a fitness base, and by the third week, something clicked.

I wasn’t exercising because I had to but because I wanted to.

It helps me feel good all day, and I accomplish more."

After six weeks of regular exercise, I was happier and felt more positive about my body.

Plus, I lost 14 pounds!

I can’t believe how much more confident I feel."

It’s motivating to have a goal."

“Waking up at 5:30 or 6 a.m. was brutal, especially at first.

The alarm would go off and I’d think, Nooo!!!”

It was wonderful, especially when I had more energy during my morning run.

The same thing happened on day 6I slept for 11 hours!

I tried to make a conscious effort to turn off the TV and go to bed earlier.

Sleeping well helps me exercise harder, which helps my state of mind, which helps me sleep.

My sleep suffered, and my mood did, too.

But that week ended on a high: I ran a 5K!

I used to be a runner, but I hadn’t done it for a year before this program.

My goal was to finish in 35 minutes, and I finished in 32!"

Six weeks later:“It used to be hard for me to fall asleep and stay asleep.

In the morning, I’d have trouble waking up and I’d be groggy all day.

Now I sleep more soundly.

The harder I work out, the deeper I sleep.

I’m doing my thingand feeling good about myself.”

Andyoga will help her relax."

The science:“Vigorous exercise may be key for people who have panic attacks,” Smits says.

“You experience rapid heartbeat and heavy breathingthe same symptoms that occur in anxiety.

But when you exercise, you might get accustomed to those symptoms and stop seeing them as negative.”

After six weeks, 40 percent no longer met the diagnostic criteria for the disorder.

Yoga works, too.

“In fact, I didn’t manage to doanythingthe first week.

After that failure, I realized I’d have to schedule my workouts like I would a work appointment.

So I took out my smartphone and the gym schedule and put classes and workout times into it.

And I discovered a hip-hop class I really love.

When I’m doing it, I’m in the moment, not overwhelmed.

I can let my stress go.”

Afterward, I felt calmand sexier!

Before I began exercising, I was having several anxiety attacks a week.

But I only had two mild ones during the program."

Six weeks later:“Exercising changed my attitude.

What a gift!”