Let’s get one thing straight: I’m definitely not an exhibitionist. Crop tops aren’t really my style, and I feel uncomfortable just thinking about posting a bikini picture on Instagram. In yoga classes, I wobble in tree pose, silently in awe of the yogis confident enough to practice in only their strappy sports bras and patterned leggings.

So working out shirtless? Yeah, not my immediate instinct.

But when a broken AC turned my high-intensity training studio into a veritable sauna, I got desperate. After the warm-up got way too warm for my liking, I hesitantly peeled off my tank top and stuffed it in my treadmill’s cupholder.

Nervously, I waited for some side-eye from the woman next to me, or for the instructor to gently tap me on the shoulder and ask that I put my shirt back on, please, no one came here to see you topless. But 30 seconds passed, and then another minute, and then I was told to sprint at a 10 percent incline and I had no energy to think about what my stomach looked like.

Why not try to be fearless?

Before I knew it, the class was over, and I was staring at a sweaty woman in the mirror, topless save for her sports bra. She looked completely exhausted, like she’d given this workout everything she had, and definitely not like she ever worried about what other people thought of her during bicycle crunches. She looked… kind of like a badass.

Facing my own reflection, I felt empowered. And if I wasn’t 100 percent secure in my body image, well, I still felt a lot better than I normally did. Under the spell of endorphins and sweat, I decided right then to take on a self-made summer challenge: For the rest of the warm-weather months, I’d work out shirtless as often as possible, both on my own and in group settings.

My goal for ditching the shirt was to become more confident and comfortable in my own skin, free of the self-consciousness that makes women work out in oversized t-shirts or not even come to the gym at all. I wanted to shake off the mentality that I should wait until I had a few abs to show off my body, or that I should hold off until I was in a little better shape to post an Instagram photo with some skin showing.

You can actually see your form without a bunch of fabric in the way.

Seeing my mostly-naked torso in multiple mirrors (with weird lighting, to boot) was a bit of a shock at first. But gradually, instead of counting down the seconds until I could put my shirt back on, I began to focus more on how I felt while working out shirtless. I could literally see my muscles working as I slammed battle ropes and swung kettlebells; I knew, without a doubt, that I was getting stronger with every rep.

One thing I learned right away was that without baggy tank tops covering my body, I could actually see my form in the mirror during class. It was easy to correct rounded shoulders or a slumped spine during class when I could spot it right away. While running, being shirtless was a simple cue to remind me to run tall, use my arms, and keep my shoulders relaxed—form adjustments that made my runs speedier and more comfortable.

The self-assurance I gained started to run on a loop: I’d conquer a tough workout feeling confident and capable, a feeling that carried over into the next.

With proper form, I became more confident in my workout abilities, which inspired me to continue picking up heavy weights and embrace tough workouts. The self-assurance I gained started to run on a loop: I’d conquer a tough workout feeling confident and capable, a feeling that carried over into my next workout and inspired me to challenge myself in new ways. I grew to appreciate the next-day muscle soreness that comes with a great HIIT workout, and I loved walking into a class knowing that yeah, this would be tough, but I was strong enough to beat it.

Confidence can build off itself.

Outside the gym and off the running path, I became more comfortable with my body in general. I realized that the old adage was true: No one cared about how I looked as much as I did. I stopped berating myself for forgetting the skinny arm pose in photos, or mentally cringing when a friend posted an unflattering photo of me. My body was strong enough to run an eight-minute mile and deadlift over 100 pounds; who cared if the cut of my shirt made my shoulders look bulky?

Now, as winter approaches, I’ll stay clothed throughout most of my workouts (I’m no masochist, and I live in Chicago, a.k.a. Chiberia). But I’ll hold on to the understanding that confidence doesn’t show up overnight, nor does it come from having the body of a swimsuit model. I’ve learned to derive my confidence from feeling powerful inside my own skin, without needing the approval of anyone else. Confidence is a mindset that you build within yourself, by taking on uncomfortable, difficult challenges… and kicking ass at them.

And knowing that really, truly, no one cares if your stomach hangs over your leggings a little bit. Promise.

Kristen Geil is a Chicago-based freelance writer who focuses on health, wellness, and happiness. She is a regular contributor to Chicago wellness blog ASweatLife.com, and her work has been featured on RunnersWorld.com, Greatist.com, and USA Today’s 10Best.com. She recently hosted a donut and wine pairing tasting party and it was the best night of her life. You can find her on Instagram @KristenGeil and Twitter @KristenGeil.