I'm neither a serious nor gifted athlete. However, what I lack in natural ability I make up in unwavering drive and an insatiable appetite for getting the best of myself - what I've come to term as my "inner badass". If you're the competitive type, you know what I mean: it's the voice in your head that doesn't let you quit. It rips you out of bed in the morning and pushes you out the door for a run. It's the one that calls it quits on a Saturday night in favour of an early morning adventure. But it is also responsible for exhausting extremes. It pushed me to train for six months to fight in a charity boxing match last year and it's what drove me to run hundreds of kilometres training for ultramarathons. It also gave me the guts to quit my job as a corporate lawyer to pursue a writing career. So after a year of change and challenge, it was time to give myself - and my inner badass - a break. For two months I swapped my morning run for a yoga session, and let my hair down. Once the time passed, I eagerly got back into training. Ten minutes into my first run I noticed something heartbreaking. Instead of the voice of irrationality egging me on, all I heard was: "Wow, this is hard work, can we stop now?" On my fifth day in a row of sleeping in, I woke in panic: where had my determination gone? To regain it, I knew I had to do something really challenging. Leadville, Colorado is the highest city in America at 3,094 metres, surrounded by snow-capped mountains all year round. It was once a bustling city known for mining gold and later silver; these days it's best known for the Leadville Trail 100 Run, a gruelling high-altitude 160 kilometre race. While I wasn't ready for such a challenge, I discovered its sister race: the Heavy Half Marathon, a 25-kilometre run starting in the town's main street, making its way up to Mosquito Pass (altitude 4,019 metres) and back. It was just the shake-up I needed to recover my lost friend. I enlisted my two running buddies, Phil and Dom, and three weeks later I was in Leadville. A practice jog along the main street the night before the race resulted in an oxygen-deprived head spin. I realised that I was ever going to complete the race, I'd have to regain my competitive streak. The next morning, I waited anxiously at the start with my running companions. The gun fired and we were off. I started at a slow pace, eager to maintain it for as long as possible. But I slowed to a walk before the top of the first hill. I told myself it was just the altitude and I would push myself later. My inner badass - now more like my inner softie - agreed breathlessly. Off the road and into the trails, I was in my element - among the trees, dirt track and blue sky. I picked up my pace on the flatter sections and surged forward. But as soon as the gradient ramped up, I was once again walking ata snail's pace. I berated myself while my body fought for more oxygen. While my internal argument continued, a runner jogged past me. Dressed in a bright fluorescent orange top which flashed in the sunlight, she was like a warning beacon. I had to pick up the pace. A little voice within told me I was running a smart race. My skill is running the descents and I took comfort that this would allow me to finish strong. And so I continued a combination of walking and running to the top of Mosquito Pass, sighting fluorescent orange blazing on the horizon. At the summit, I took a quick happy snap, started my descent and began to fly. "You go girl!" shouted a fellow competitor as I overtook him. I could feel my determination stirring from the depths, locked on to the challenge of catching - and then passing - the fluorescent runner ahead. Pushing my limits, I strode over the loose rocky path, risking a broken ankle to chase my goal. Soon, I blazed past fluorescent orange, and also overtook a pink, a purple and a few other colours of the sporting apparel rainbow. Then something happened. As the trail flattened, lethargy set in again and I slowed to a walk as I gasped for air. Fluorescent orange zoomed past. A game of cat and mouse ensued: I nipped at her heels on the descents, but I lost ground on the uphills. With only five kilometres to go, I could see her ahead. Tunnel vision set in. If my inner badass wasn't going to return on its own, I was going to force it out. Letting my legs go, I propelled down the hill. I caught her and edged past. Victory! Or so I thought. In the last kilometre she gained on me. My reserves were empty. The combination of altitude, a mental fight and over three hours of running left me spent. Through sheer willpower and momentum, I tipped over the finish line, just ahead of my nemesis. After the race, I meekly walked up to fluorescent orange to congratulate her, hoping she hadn't felt the mental lasso I had tied around her almost the entire race. She returned the compliment. "I kept thinking the whole race that I've got to keep up with the girl in the purple shorts," she said. "You were badass out there."