Kayla Harrison is fighting for the UFC women’s bantamweight championship Saturday night at UFC 316.

A two-time Olympic gold medalist, Harrison dominated her five-year run in the Professional Fighters League, winning 16 of her 17 bouts. The only American to ever win Olympic gold in judo, she also won her first two bouts in the UFC. And she enters the title bout as a colossal favorite.

But Harrison was not always the favorite. In fact, she was far from it.

“I’ve been through the worst of the worst,” said Harrison. “Nothing in that cage can break me.”

Harrison’s father committed suicide. Her sister battled addiction. And she lost her innocence — and confidence and self-worth — as a teenager when her coach back in Ohio sexually abused her.

On the cusp of tragedy, Harrison’s mother made a life-altering decision by moving her daughter to Boston. That is where Harrison trained with the Pedro family, who instilled an entirely new sense of purpose and pride in her life.

“I believe in God,” said Harrison, 34. “In my hardest moments, God gave me the voice to say, ‘I won’t give up.’ Moving to Boston, that was God in my life. I was this 16-year-old car wreck — I was suffering from post-traumatic stress disorder and I was suicidal. My mom didn’t know what to do with me, but she knew that if I didn’t have a goal, if I didn’t have something to wake up for, then I was going to end up dead or addicted to drugs. So she moved me to Boston.

“And the Pedros didn’t just change my life, they saved my life. They believed in me when I didn’t believe in myself. They gave me a safe place and a lot of tough love. They didn’t baby me — they built me into an unstoppable force. I attribute a lot of my mental toughness and success to them.”

Harrison’s unbreakable spirit has been visible in the build to her title fight at UFC 316, which takes place at the Prudential Center in Newark, N.J. She successfully cut weight, hitting 135 pounds on the scale during Friday’s weigh-in, an agonizing ordeal for someone whose natural weight is closer to 160. And she has one more significant obstacle in her way, and that is reigning champion Julianna Peña.

“It’s going to be a battle of will, skill, and heart,” said Harrison. “I feel like I’m the better fighter everywhere — a better striker, a better grappler, and a better fight IQ. I just need to go out there and fight my fight. She’s going to be tough, but I’m pretty tough, too.”

Throughout the fight realm, it is not out of the ordinary to see fighters sell their soul in pursuit of gold. Yet Harrison’s story is different. It is that search for greatness which defines her. A favorite after a lifetime as an underdog, Harrison enters this title bout in a position of power — and she intends to fight for those who cannot.

“I’m fighting for the voiceless,” said Harrison. “I’m fighting for the victims who don’t know that they’re survivors. I’m fighting for the people who don’t want to wake up. I’m fighting for the single moms. I’m fighting for Boston, I’m fighting for my country, I’m fighting for God. And I’m so excited to prove to the world that I am who I say I am.”