At mile nine in my most recent half-marathon, I thought I might faint. Not training for the race had finally begun to catch up with me: My legs felt like they were about to fall off, and I wasn’t sure how I was going to make it through the next four miles.

Out of desperation, I tried a little experiment: I struck a Wonder Woman-style pose in the middle of the course in a last-ditch effort to perk myself up, mentally and physically.

The Psychology of Power Posing

This idea wasn’t totally insane, I promise. I had just finished reading Presence, a book by social psychologist Amy Cuddy whose famous TED talk on the science behind “power poses” and the overall power of body language forever changed our view of how our physical state affects our mental one.

The thinking behind power posing is pretty simple: Put your body in a powerful position (e.g., chest out, hands defiantly on your hips or triumphantly thrust into the air) and you’ll actually start to feel powerful.Power posing: brief nonverbal displays affect neuroendocrine levels and risk tolerance. Carney DR, Cuddy AJ, Yap AJ. Psychological science, 2010, Sep.;21(10):1467-9280. It’s the same idea behind “fake it ’til you make it” or giving yourself a pep talk in the mirror à la Jessica’s Daily Affirmation.

In Presence, Cuddy recommends spending a few minutes per day in a power pose to boost your mood or altering your body language in real time to up your confidence in the middle of a stressful situation. Still, I wasn’t sure if her strategies would seriously work for me—or if it was just a placebo effect, a fluke. So I decided to try power posing in several different scenarios—and my month-long experiment began.

Mile 9 of a Half-Marathon

Back to my almost-failed race. In her book, Cuddy points to existing research behind how the classic hands-in-the-air stance runners have as they cross the finish line actually affects their physiology—the strong stance may physically make their bodies stronger.

Still, my mid-race victory move felt sorely out of place (and I got some confused looks from fellow runners). I even threw in a cheesy, confident grin—I was that desperate for any kind of energy boost.

Despite the goofiness, it actually worked. Maybe it was because focusing on my body language took my focus off the pain in my knees, but whatever was going on, it got me across the finish line—with fists raised in celebration, of course.

Meeting the Parents

The next challenge came with high stakes: I was meeting my boyfriend’s family for the first time. As if that weren’t stressful enough, there was an added layer of complication. My boyfriend is well versed in social psychology (he’s the one who turned me on to Cuddy’s research in the first place), and he routinely calls me out when my body language is closed off or defensive.

What’s more: I know his family is hyper-attuned to body language and nonverbal cues, so crossing my arms or slouching at any point during dinner would be a dead giveaway that I was feeling nervous or insecure. I’m screwed was pretty much the only thing I could think about the day before the dinner.

Since I couldn’t exactly sit at the table with my hands on my hips and chin angled defiantly into the air (something tells me that might backfire), I decided to spend a couple of minutes prepping in the mirror—another tactic Cuddy recommends. Assuming a power pose in my bathroom, I repeated the pep talk my mom gave me earlier that day on the phone.

And holy crap did I feel stupid. Standing with arms akimbo telling myself what a catch I was did not exactly a confident woman make. By the time I walked into dinner, I felt even more jittery—the solo pep talk was clearly not my thing.

I did try to keep tabs on my posture all evening and I was definitely more aware of what my body was signaling (chest open and shoulders back = good; arms crossed, hunched over = insecure). And as I got to know his family, I focused not only on what I was saying but also on what my body was saying. Halfway through the meal—head still held high—I felt confident and relaxed (though I’m not sure if I should thank my body-language knowledge or my BF’s great family for that).

Paddle Boarding

I still wasn’t totally sold that power posing was actually changing my brain chemistry the way Cuddy’s research had shown. Was I actually any happier or in control of my confidence?

On a recent trip, I went paddleboarding—an activity I usually love. I’ve never felt the kind of anxiety some of my travel companions were feeling about getting on the board and heading out into an open ocean.

But about 20 minutes into the adventure, I felt undeniably anxious and insecure. Suddenly I started thinking about grad-school applications, my long-term career goals, the future of my relationship—and if my life in general was moving in the right direction.

What the heck?! I thought to myself. It’s a gorgeous day. I’m doing one of my favorite activities. I’m on the water. Yet my mood was slowly but surely darkening. All the latent angst in the back of my mind about whether what I’m doing (read: who I am) is good enough pushed its way into my consciousness—demanding my attention.

That’s when I noticed my body language. Paddleboarding requires you to stand in a kind of hunched position: knees bent, hinged at the waist, shoulders slanted down to paddle—the exact opposite of a power pose.

Then it hit me. Despite all of the environmental cues that I should be totally killing it, I felt the most insecure I had in a long time. In fact, I almost sat down on my board and cried.

But thinking about my body language, I did the opposite. I stopped paddling into the anxiety and stood up on my board. I tilted my face up toward the sun. I raised my paddle high above my head. And I could literally feel the moody clouds in my mind lift.

Consider me a body-language believer.

The Takeaway

Since my experiment ended, I might not be fiercely placing my hands on my hips at every party or meeting, but I have made adjustments to my posture in real time. When walking into a room full of strangers at a networking event recently, I consciously uncrossed my arms—my go-to slouchy pose when I’m feeling intimidated—and made a note to keep my shoulders back. Someone I’d been hoping to meet actually approached me—talk about a tangible confidence boost.

Overall, the experiment had mixed results—like I said, the whole pep-talk-in-the-mirror thing just made me feel dumb. But I did gain massive respect for the effect body language can have on mood. Paying attention to my posture and how I hold myself will continue to play a huge part in feeling more at ease and confident in stressful situations for now and, I hope, forever.