He lived in the building next door and we went to the same gym. Tall, dark eyes and soft skin. A nervous temperament, except when he was running. He was always running: around the neighbourhood, past the coffee shop at the exact moment I looked up from my window seat, up the long stretch of road as I headed home in the opposite direction.

I never noticed him until I became single, and then all of a sudden he was everywhere. It was as if the universe was begging me to pay attention. I felt too shy to make a real move, but I followed him on Instagram and started walking home with him when our gym classes coincided. The first time I plucked up the courage to ask if he was heading my way, my hands shook so much I thought I might fall apart. I had a crush! Even at the big old age of 25, my prefrontal lobe just about fully developed, I had an all-consuming crush. I felt like a schoolgirl. What was going on?

That feeling is created by dopamine, the neurotransmitter responsible for motivation, pleasure and reward-seeking. As Nicole Vignola, neuroscientist and the author of Rewire: Break The Cycle, Alter Your Thoughts And Create Lasting Change, explains, when we become interested in someone, we are motivated to both attain them and to gain information about them, eg who they are and what they do.

“Our dopamine levels increase, especially in response to motivation, but also to the pleasure of potentially getting the reward,” says Vignola. So, when it comes to crushes, the pleasure is in the pursuit. This is why we end up driven not just to be around our crushes, but also to look for clues about their availability or compatibility through social media or mutual friends. And, wouldn’t you know it, these feelings become even more intense when we become engaged in a game of push and pull. When you never know what you’re going to get, the drive to find out is intensified.

“The attraction consumed me”: why having a crush as an adult is so intense