The biggest struggle of fighters that most people couldn't claim to understand is the cut. Not the training or the fight itself - those are things you do while all gassed up. It's the final 24 hours when your body's on empty, your head is spinning, and all that's left is to suffer your way down to the scale.
Moving up had freed Nico Carrillo from that struggle, and rather than endure the misery of the cut, the camp became a time for him to focus on sharpening his skills, not dropping his weight. And this, he said, has made all the difference:
"I'm just, I feel that I'm just in love with the sport again," Carrillo said during the post-fight interview. "I'm in love with that again. I've not enjoyed a fight camp like this in so long."
Watch the full interview below:
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Nico Carrillo thankful to have 'kept all the demons at bay' in statement finish of Sitthichai
Another challenge fighters face is bouncing back after a particularly bad knockout.
Nico Carrillo's knockout loss to Nabil Anane at ONE 170 wasn't a simple career setback - it became a mental hurdle for him to navigate. He's done months of work, suffered through a brutal cut, and in a flash - it's over. Didn't even get past the first round.
It's the kind of that's enough to make you question your decisions, your skills, and perhaps even your place in the sport.
But at ONE Fight Night 30, Carrillo stepped into the Circle as a featherweight for the first time and came out a reborn fighter.
"I'm just so happy and pleased with myself that I kept all the demons at bay," he said. "All the voices in my head that were scared, and I didn't want to feel that feeling again. In order to see the sun rise again, you need to get out in the shades."
Watch Nico Carrillo in action at ONE Fight Night 30, available for replay with an active Prime Video subscription.