Toughness manifests itself in very different ways. Athletes are viewed as tough when they play through injuries. Fighters are considered tough when they take blows and keep moving forward.
Abner Mares, the classy WBC featherweight champion, is tough in that regard.
But Mares showed his toughness long before the world knew his name. Mares, 27, is now one of the world's most popular boxers, and will defend his belt against power-punching Jhonny Gonzalez on Saturday at the StubHub Center in Carson, Calif., in the main event of a Showtime-televised card.
Long before he earned fame and some fortune, he survived by eating out of trash cans, living on his own in a foreign country at 15, sleeping on floors and fending for himself.
Mares was born in Mexico into abject poverty, but even when his family emigrated to the U.S. when he was seven, their lot in life was not much better. Mares was still living in poor conditions and didn't have the casual suburban upbringing.
He showed a skill for boxing at an early age and so when he turned 15, the former gang member was sent by his parents by himself to live in Mexico so he could pursue a spot on the Mexican Olympic boxing team.
He represented Mexico in the 2004 Olympics in Athens, Greece, but the day-to-day grind was hard.
"I am the person I am now because of everything I went through as a child," the friendly and affable Mares says. "All that, eating out of trash cans, being in a gang, sleeping on the floor because I had nothing, living on my own at 15, that made me who I am. I grew up fast. I had a different life, but it's all good.
"I'm here today because of all of those experiences. I became a man because of what I've been through in my life."
When he first returned to Mexico at 15, he was desperately lonely. He phoned his mother every day, pleading to be allowed to return home.
But his parents believed making the Olympic team would be best for his future and made him stay. Eventually, Mares adapted.
And he's been doing that ever since. He's become successful as a fighter not only because of his sheer toughness, but also because of his ability to adapt in the ring.
He's faced sluggers, boxers, southpaws and every style imaginable, and has rung up a 26-0-1 mark with 14 knockouts.
He's beaten some of the better lighter weight fighters of his time – he's bested elite opponents such as Anselmo Moreno, Daniel Ponce de Leon, Vic Darchinyan and Joseph Agbeko – and he's never shied away from a challenge.
Mares said he's better because of the elite opponents he's faced. When you're facing championship-caliber opposition every time out, it's either figure out how to survive or get content with being an also-ran.
Mares is no also-ran. He learned how to survive and flourish.
"I've fought nothing but the best, and I can't begin to tell you how much that has helped me," he said. "Everyone I've fought I've learned from and taken something from them. It's helped me to progress."
He'll have to survive Gonzalez's vaunted power. Gonzalez has 46 knockouts among his 54 wins and is one of the hardest hitters in the lower weight divisions.
Mares' toughness didn't escape the notice of Gonzalez, who isn't expecting to run over him with a power attack.
"With Mares, you know he's a good fighter and he knows what he's doing in that ring, so it's important to have a plan and execute it, because he's very good," Gonzalez said. "I believe in my power, but I can't go just for knockouts because he knows how to [deal with] that. I have to follow my plan."
Mares' plan – surviving a desperately poor childhood and living alone at an extraordinarily young age – shouldn't be a blueprint for others.
But his willingness to adapt and to not make excuses should.
Despite all of his disadvantages, Abner Mares has become one of the most complete fighters in the world and is an idol to thousands of Mexican and Mexican-American fans. His story resonates with them, because so many of them have been in his situation.
You have to be tough to take a punch, but taking one isn't the only way of proving toughness.
A 15-year-old Abner Mares proved that.