The towering Thomas — he’s 6-foot-8 — is “Big Jo” to many of his clients, who range from Blackhawks players and their wives to a friend’s autistic brother. As fitness director of Flats, the rental properties of Cedar Street Companies, the 34-year-old River North resident teaches notoriously high-intensity classes at a growing number of locations. Here’s how the former Western Illinois defensive end and ex-MMA fighter works on his well-being.

Fighting by chance

“My roommate after college was an MMA fighter. In 2005, he was fighting in Costa Rica and asked me to come; he said, ‘I’ll tell them you’re my sparring partner and you’ll get a free ticket.’ The day before the fight, he destroyed his knee, so they asked, ‘Could your sparring partner go in?’ I fought and won. From there I went right to pro. The first six months were great. But I had to stop in 2012 because of concussions from football.”

Spinal crunch

“Right now, I have a broken back. They’re tracing that to football, too. It’s called a pars fracture, a break in that little wing that hangs off. I’ve had to slow down my boxing and evolve my training. My goal is to fix it without surgery. It’s just another math problem to figure out.”

Training routine

“I work out in the morning, five days a week — two minutes of jump rope, then one minute of pushups and one minute of pull-ups, for 15 rounds. It’s a good mix of cardio, anaerobic work, and body weight training. I’m done lifting heavy. Who gives a shit how much you can bench if you can’t walk down a flight of stairs? I’m finally enjoying working out. It was a job before. Now there’s a purpose — to be healthier.”

Perfecting posture

“I have to make my core indestructible to protect my back. I’m on my feet 14 hours a day, so I’m always mindful and conscious of how I stand and walk. I try to straighten up, draw my bellybutton back to my spine, making sure my lower ab muscles are tight and I’m breathing through my diaphragm.”

Eating plan

“My main goal is keeping my caloric intake between 3,500 and 4,000 so that I stay within five pounds of my fighting weight. I do intermittent fasting, mostly because I’m so busy. If I’m crashing during the day, I’ll take some Isopure protein powder. But I often make it until 7 p.m. before my first meal. I [have an endorsement deal with] Factor, which predelivers meals. From 7 to 10 p.m., I’ll eat about four of their meals. If I’m still hungry, I eat apples and peanut butter.”

Morning joe

“I wake up at 5 a.m. and rip about six espressos. I train my first client at 6, then have another six espressos. It’s probably way more than anybody should be drinking. I take other supplements in the morning too — supergreens and powdered beets — that are supposed to give me more energy, but who can tell with 18 espressos?”