As the head of talent management and human resources for Asia-Pacific at financial services provider State Street, work and family had always taken priority.

But she had her heart set on finishing Trailwalker by the age of 45. And the Irish-born woman knew it was now or never this year.

Ten months ago, her training hikes would last just 10 minutes. "Sometimes I would take a taxi home - it really was that bad," she says.

"But I have been very disciplined. I have been walking every evening when I get home. Slowly and surely I've increased the distance."

By the end of March, she could walk about 15 kilometres at a good pace, even jog a little bit. By the end of April, she had signed up for Trailwalker.

And she says training has taken over her life. She spends every evening and most weekends hiking, and even handles nightly work calls on the trails.

Completing the race, she says, will "probably be the biggest thing I've done besides giving birth to twins".

"I tend to set really unrealistic goals for myself," she says. "But if I set them, I know that I will achieve them."

How great an impact something as simple as hiking can have. There are 144 steps near where I live. It used to take me 30 minutes to get up them. Now it takes me only two-and-a-half minutes.

I've also been surprised by the change in the way I view food, as the concept of having to fuel for endurance is really new to me. I haven't restricted myself at all - I still enjoy a few glasses of wine and treat myself - but my weight has dropped. Training for Trailwalker has stopped a cycle of yo-yo dieting.

There was one time early on when I was going up Ma On Shan, and I completely ran out of energy. If I could have called a taxi, I would have. I even tried to bribe the paragliders to carry me down. Mentally, I had to pull myself together and say: "This is tough, but you can do this, and you know you're going to feel better once you achieve this."

I think it's about mental agility in the end - shutting out the body and keeping focused on the end of the next stage.

I'm addicted to hiking now. You meet amazing people, see amazing things and feel fantastic afterwards. In July I climbed Mount Fuji in Japan and couldn't believe how far I'd come and how much I could achieve in just a short while.

I will keep up my new routine, but I probably won't walk every night. As a team we are already setting new goals, and we haven't even got through this Friday yet. But we will. We will finish it and then start training for something else.

In my mind I have. I'm not even thinking about not completing it, I'm just visualising each stage and looking to that finish line. I would need to have a broken leg to stop me. I've done enough walking and training that I know my legs will take me there. The rest is mental.

I've changed my mindset. Before I would put work first and say to myself: "I can't do it as I need to do a night call." But the training has to fit in somewhere. In the past few weeks, as the training has ramped up, with my colleagues' support I have actually taken calls while out walking.

Just do it. Sign up. Set a goal. It doesn't matter how far you can walk in months one to three. Don't think of it as 100km - just keep building up really slowly, even if it is just an extra five minutes each time. At some point have a midway check and see how you're progressing. Reset the goals if you need to and work a bit harder until you feel you're able to do it.