The summer after being diagnosed with lymphoma on, of all days, Sept. 11, 2001, Tom Giuliano did something crazy. While going through chemotherapy treatment, he competed in his first Iron Man competition.

Thirteen years and ten more Iron Man competitions later, Giuliano is still at it. Despite his chemotherapy treatment, Giuliano is gearing up for the Mercer Island Half this weekend, in which he will compete with his daughter, Claire, and her husband Justin Houck.

Giuliano, 62, says running is part of his identity. There’s a whole life and lifestyle with running, mentioning the friends he’s made over the years through running. Giuliano tries to exercise six days a week, and will wake up at 5 a.m. to run an hour before work. He does it because he’s addicted to it.

“I ran my first marathon forty years ago. What I’m doing is continuing the things I love and basically being me as best I can. I’m not out to prove anything, I’m just trying to enjoy it.”

Since his initial diagnosis, Giuliano, who works as an anesthesiologist, says the lymphoma has morphed into leukemia as well, which isn’t uncommon. Giuliano says being an anesthesiologist helps him have a better sense of the numbers when it comes to cancer. “So many people have cancer, you’re lumped into the same crew,” he says. “You have time to live. Within hundreds of thousands of people, each has individual outcomes. I’ve hoped mine would be a good course.”

His mantra has been something another patient told him when he first started chemo: “It might kill you someday, don’t let it kill you every day.”

“He almost lives as if it isn’t there,” says Claire. “And that’s not to say that the chemo has light effects on his body, because it doesn’t. It’s a very harsh thing. But he keeps up with his career, on top of his training, which is pretty incredible.”

Giuliano began racing with his daughter when she was in sixth grade, signing up for the Rotary Run 10K. Claire, 27, says her father pulled her along the whole way, as the whole race was pretty far for her at the time. They continue to race usually every year, with Giuliano in the Half and Claire in the 10K.

“We race together and we train together, and we’re always in tune with each other’s training to motivate each other. Racing is almost like this father-daughter tradition we have,” she says. “It’s nice to know he’s out there running, so if he’s having a hard time and I am too it’s all good.”

Giuliano’s wife, Laura Macht, says it’s not unusual for him to train for Iron Man while doing chemo.

“I’ve had concerns, but not like the first time when I literally thought this could kill him. Now I just think it’s kind of nutty,” she says. “At the end of the Iron Man competition, he’s laid out on the bed, and I said ‘you know, you don’t have to do this next year.’ And he says, ‘oh no, I’ll sign up tomorrow.’”

“He’s been sick for five and a half months, really in bad shape and not feeling well. He started chemo in January, started running again shortly after and the minute he started feeling a little better, he told me he was going do the half marathon. I was like, ‘are you crazy?’”

Laura remembered her husband a couple years ago being so ill by the time he started chemo, he could barely run a mile. He still ended up doing the Iron Man competition anyway the following summer. “He was so ill, I was surprised he still did it. And he was happy about it,” she says.

Some days, the running makes him feel better, something that might surprise those aware of his condition. “In the beginning, I never would’ve guessed that because I felt so crummy,” he says of feeling better after a run. “I’ll feel good, better than when I started. You can be in a state in fatigue or nausea and you’d be surprised what you can do through it.”

But when the cancer gets bad, it’s not easy to go out and get a workout. Some days instead of making you refreshed, running wears you out. Giuliano says you usually don’t know until halfway through a run it’s going to be one of those days. You don’t always know until you try.

When it is one of those days, Giuliano says he’ll slog on through it. “I never turn around and go home after the first few steps because I got to find out.”

For the Mercer Island Half, Giuliano admits he’ll be taking it easier than usual. “I’m preparing psychologically for a very slow time,” he says. “This latest flare-up of cancer was accompanied with a couple illnesses that knocked me back as far as I’ve ever been knocked back. This won’t be my usual time; I’m setting up to just cover the distance.”

But Giuliano says he keeps doing it because being physically fit not only makes him feel great, but also leads to a kind of confidence.

“When people take on a sport, they make a discovery of ‘wow, not only do I feel great, I feel confident.’  You have a goal that seemed impossible before but see, wow, I can do this, I can do something. It doesn’t have to be a marathon, it can be a 5K. Anything is better than nothing. You can always do something. I think I’m incredibly lucky to continue to do what I love so much through all the treatment,” he says.

And on Sunday, he doesn’t believe he’ll be alone.

“I guarantee you on the starting line, there will be people like me. There are a lot of people like this; those are the lifelong runners.”