In 2023, at age 58, the author was trekking the 80-mile Tour du Mont Blanc in the Alps when she found herself not trekking so much as frozen on her hands and knees, crying, while other hikers bopped past her like water around a stone. "Why can't I move?" she wondered. Spoiler: it wasn't her spine. It was the fear she'd been carrying since childhood.

As a kid, she was the one always picked last in gym class - and honestly, she'd have picked herself last too. By any measure, she was the most physically awkward kid in her year group. Other students bullied her, and she was ashamed of her body. Then, at age 10, she was diagnosed with scoliosis, along with severe lordosis (part of her lower spine running almost parallel to the ground) and spondylolisthesis (one vertebra sitting noticeably out of line with the others). When she first saw the X-rays, she was stunned by the abrupt angles and unnatural twists. It looked like chaos. The feeling of being "weak and weird" settled in for good.

Her parents took her to a hotshot orthopaedic surgeon in New York, who delivered a genuinely terrifying prognosis: the displaced vertebra was very dangerous, and with any fall or bump it could slip forward, sever her spinal cord, and leave her paralysed. He recommended a major operation to chisel bone from her thigh and fuse seven vertebrae in her lower back, followed by a year in a body cast. The surgery was scheduled. She was horrified.

Meanwhile, the world became an unrelenting obstacle course where every bump, staircase, or crowded hallway seemed specifically designed to paralyse her. She became afraid to move at all. A second opinion from another orthopaedic surgeon offered a rather more measured take: many people live with this condition, the risk of paralysis was actually quite small, and they could skip the operation and just keep an eye on her spine. She took his advice - but for decades carried a low-level terror inside her body and remained timid about any physical activity.

By her 30s, she was working in increasingly senior executive roles with endless travel, long hours, and lots of stress. She was exhausted all the time and in agony after standing for an hour. She feared her weak body would sabotage her career.

Then she relocated to Colorado, where a colleague invited her on a bike ride to explore her new hometown. She said yes, expecting coffee and maybe 30 minutes of gentle cycling. Instead, their first ride was 20 miles into the countryside. She was astounded she could do it, given she hadn't really exercised, ever. The next time, they rode 50 miles - and she survived that too. Before long, they were doing 100-mile rides through the Rocky Mountains, biking for entire days, sometimes climbing to altitudes of more than 11,000ft. Each ride challenged a self-limiting belief she'd carried since childhood. Could she actually be strong? She started to gain energy and feel less burnt out at work, too - she could now present a one-hour keynote without wanting to collapse at the end.

When she turned 40, she asked a doctor to do a safety assessment on her spine. He compared her current X-rays with those taken at age 16 and determined there had been no significant movement or degeneration to the vertebrae. He told her she could pursue fitness with very few limitations - which felt revolutionary. She started working out with a trainer and, for the first time in her life, stopped thinking about her body only in terms of how it looked or what was wrong with it.

Frozen on that Alpine peak at 58, it occurred to her that it was not her spine but her latent fear that was paralysing her. She took a deep breath and crawled up and over the summit.

For most of her life, she'd treated her body as an ungraceful and unreliable adversary. But having biked in the Rockies, trekked in the Alps, and fallen off a stage during a keynote presentation - all without paralysing herself - she realised she's not so fragile after all.

Now, at 60, she is running and jumping, doing push-ups and pull-ups, and lifting heavy things repeatedly. Transforming her physical strength has changed her at the deepest level and redefined her limiting beliefs about what is possible in every part of her life. She is no longer ashamed of her body; it has become her ally. And she bets that now, standing among her peers, she would even get picked first in gym class.