WHEN I FOUND OUT I HAD MS.I THOUGHT I'D NEVER RUN AGAIN.

I checked the pins on my bib, shimmied my spandex shorts into place, and teed up the stopwatch on my wrist.

I closed my eyes under the expansive, blue Big Sky above, inhaled the Montana mountain air, and listened to the hum of the thousand or so of us waiting for the race to start. This was the 5K crowd, livelier and less focused than the folks who'd be lining up the following day for the 2022 Missoula Marathon. Some were probably doing the 5K as a shakeout, a quick warmup before the big dance tomorrow. But for me, this was the big dance.

I pressed Play on my mix. The first song, "Genesis" by Justice, was, I'd learn later, a bit aggressive out of the gate. But like every starting line I'd toed since high school, I couldn't shake the mentality. I wasn't there to participate. I wasn't there to finish. I was there to win. Except this time, I knew I couldn't.

I tightened the laces on my oversize Hoka Bondis, shook out my legs, and then-mindlessly, automatically-followed the same prerace ritual I'd had since I was 14: hopping high in place like a frog, heels hitting my butt. I looked more like a drunk flamingo, though; my right leg was the only one strong enough to jump, with my left leg landing awkwardly in its hard plastic brace.

FOUR YEARS EARLIER, AT AGE 36, I WAS DIAGNOSED WITH MULTIPLE sclerosis-a chronic, degenerative disease of the central nervous system that affects the brain, spine, and optic nerve. For several weeks prior to my diagnosis, I'd been experiencing numbness and tingling along my left leg, which I thought was because of all the horrific shots-sometimes three a day-that I'd been getting as part of my in vitro fertilization (IVF) process while desperately trying to have a second child. I figured we'd hit a nerve. No big deal.

But then I started limping. Even still, I brushed it off. A slipped disc, I reasoned, likely brought on by the weight gain from IVF. My friends affectionately nicknamed me Peg Leg. We were making jokes because we were sure it was nothing-something orthopedic, something ordinary.