He's turned hopeless amateurs into thriving professionals and transformed terminal cancer patients into champion athletes. He even gave last year's Ms. Olympia the single piece of advice that changed the trajectory of her stunning career.
The taut bodies and shiny trophies, however, are not all that the 62-year-old is after. That, he says, is more than skin-deep.
"The most fulfilling thing is not about winning," said Del Corso, a retired champion bodybuilder and Mr. New Jersey 1988. "It's about making someone feel like they're somebody."
Coaching comes as naturally to Del Corso as the sport itself.
He developed a fascination with bodybuilding when he was just nine years old, visiting his grandmother in Seaside Heights.
"I saw a guy with all these muscles and it never left my mind," he said. "That was something I wanted to be -- he looked like a Marvel comic."
Del Corso was 14 when he got his first weight set and bench and began working out in his dad's garage. It wasn't long before guys in the neighborhood joined him, each one chipping in $5 a month for new equipment.
He opened his first gym -- "Guy's Gym" -- in his early 20s inside of Paterson storefront, then later relocated to Hawthorne.
There, he built the body that crowned him champion in nearly every division all the way through his late 50s.
The gym closed after 30 years, and in 2009, Del Corso retired from the stage.
"Like any athlete, it comes to an end," he said. "I went out happy."
Retirement was even more blissful than Del Corso had imagined.
He enjoyed the newfound downtime with his wife and two daughters while welcoming two new granddaughters into the family. He also picked up more gigs as a personal trainer, working closely with local athletes.
Disaster struck in 2015, though, when Del Corso was diagnosed with cancer. Then he suffered a heart attack.
Life as he'd known it changed completely.
Instead of letting his health sideline him completely, Del Corso used his ailments as opportunities to help others grow.
"I was out of work and a bunch of people I was training at the time came up with this idea," he said. "They offered to pay me a couple bucks a month for me to send them workouts. I would be their coach.
"These bad things happen in your life but there are so many good things that come out of them."
Those blessings include hundreds of clients from across the U.S. whom Del Corso has worked with -- all from the comfort of his living room recliner.
He started with a handful but "then it just skyrocketed," said Del Corso, also an NPC and IFBB judge and head expediter for bodybuilding veteran Steve Weinberger. "It just started multiplying."
Now, he averages approximately 80 clients per day and is back in the gym training.
Part of Del Corso's magic is that he's not just a coach to his clients -- he's also a friend. He's given addicts new reason to live and helped terminal cancer patients on feeding tubes earn their pro cards.
He's given his clients meaning.
Del Corso has been "nothing but a beam of light in my life" for three-year client Christina DiBella of Hillsdale, an East Coast and multi-class champion.
"I went through a toxic breakup that really messed with me mentally, and he was always there to keep my mind on track and make sure I knew my worth," she said.
Del Corso texted DiBella unprompted and at one point began sending her Bible verses -- an early-morning ritual of his that go to different clients, friends and family members.
The verses haven't stopped since, DiBella said, and hopes they never do.
"He truly treats me like one of his daughters," she said. "I know a lot of his other clients can attest to this as well."
The most gratifying part about coaching for Del Corso is not the shiny trophy. It's not the title or the medal. It's the breakthrough -- large or small.
"I'm taking somebody that thinks they have no genetic potential and so down on themselves, and making them something that they thought they would never be," he said.
"Whether they get their pro card, take first place or last place, they walk out feeling like something they never felt like before," Del Corso said. "That's the greatest accomplishment as a coach."
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