It's Thursday, lunchtime, it's cold outside and I'm not in the mood for a run. So I decide to go for a swim. I want to discover something new about myself:

"How far do I have to swim until the wish to stop is gone?"

I experience that every time I run, but I never swam non-stop far enough to feel the same in the water. All I have to do is to defeat the urge to stop at the wall.

I start swimming, breathing and stretching my arms, it's going well. After a while, I look at the watch, it's been nine minutes and I feel good. I want to make it more challenging, so I imagine myself at the Guelph lake, swimming in open water. It's going to help me prepare for my next triathlon. I get the images in my mind and then the sensations follow. Suddenly, I feel out of breath as if I can't swim anymore, as if I need to let go and drown. I stop swimming in the middle of the pool, agitated like waking up from a nightmare, treading water.

"What's going on?! I can swim, what's coming over me?!"

I tell myself I need to get to the wall, I don't even swim correctly, I move towards that wall and those ten meters feel like an eternity. While I struggle to get there, I'm thinking:

"Yes, I am afraid. Yes, I am afraid. I won't fight that. But this fear is not me. I'm feeling it but I'm going to place it somewhere... it is at the wall, it's looking at me, waiting for me to fail. I am afraid, fear is not me, I'll act as myself, I will continue swimming."

This is going to be a turning point for me. I get to the wall, I turn and keep swimming. This is a simple movement for so many people, even for me when I'm not trying something new. But these twenty meters were a defining moment to overcome my fear.

How could I feel a paralyzing fear in a safe and controlled environment that I know so well? In the book I'm reading - Mindsight: The New Science of Personal Transformation

• I learned that the brain does not differentiate between what I'm living and what I'm imagining. So, for my brain, I was at the lake, with dark water and nothing to hold on to.

At the Guelph lake, when I tried open water swimming for the first time, I revived memories of when I was a child having fun in the ocean. There was always someone at the beach telling me I was too deep and would drown. Nearly forty years later, my brain dug into that association and triggered my defence mechanisms.

But today, I have new tools. These tools are my thoughts and they spread like water. My new thoughts shape how I face fear and how I let myself move away from freezing and move like the water that surrounds me.