Man Runs by Dad's Hospital Every Day During Cancer Treatment — and Again in Marathon 2 Days After His Death (Exclusive)

Michael Hartnagel continued a tradition he started with his father, even in a heartbreaking moment

• Michael Hartnagel and his father took up running together several years ago

• His father was going through treatment for prostate cancer at the time, but still strived to run a mile a day when he could

• As his father's health declined, Hartnagel continued their tradition, and has turned it into a tribute to his dad since his death

A man who loved running with his dad shared an emotional moment on TikTok during an ultramarathon — tearing up as he passed his dad's former cancer treatment center just two days after his death.

Michael Hartnagel, 29, tells PEOPLE he's been running for five years, and took the sport up following a career in baseball.

In January, 2017, his dad was diagnosed with metastatic prostate cancer, though maintained a positive outlook despite the devastating news.

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"He was always the most active, healthy, positive guy you would meet, and cancer didn't change that," Hartnagel says. "Through his battle, we started running together and it was his way of fighting back against cancer."

In January 2021, Hartnagel's dad even started a streak of running at least one mile per day outside, "as a way to push himself and stay active." By that April, he had to stop due to his health — but Hartnagel continued, running at least one mile per day to keep the tradition alive.

"As his cancer fight progressed, running was my way to feel connected to what he was going through, so I would seek harder and harder challenges for myself to take on," Hartnagel says.

So, while his dad underwent treatment at Indiana University's Simon Cancer Center, Hartnagel would take his runs outside the facility, as a way to "show up for him so he didn't feel like he was alone in his fight." His dad would often appear at the window to watch.

In July 2023, the family received the news that there were no more treatment options. It was then that Hartnagel set out to take on something both physically and emotionally challenging in solidarity.

With September being Prostate Cancer Awareness Month, he set a goal to run 157 miles in three days.

"As we got closer, the understanding that [Dad] most likely wasn't going to make it to the run became more real," Hartnagel tells PEOPLE. "But the goal of the run for me personally was to do something so challenging that I could catch a glimpse of what my dad endured during his fight. The courage, the strength, his 'Stay Positive' mantra that he showed me, just inspired me so much."

Hartnagel's dad died on Sept. 26, 2023 — just days before Hartnagel laced up his shoes to run 157 miles. Two days later, he was on mile 77, passing the cancer center he'd run by so many times before. Only this time, his dad wasn't looking out the window to cheer him on.

"Nothing would prepare me for that moment, when I looked up at the window he used to be at, and not seeing him there," Hartnagel says.

As difficult as the moment was, Hartnagel says he also felt at peace "knowing that he didn't have to fight anymore."

With his dad there in spirit, others — hospital staff, his dad's nurses, oncologist and the cancer center director — stood by to offer Hartnagel support.

"Running has 1000% brought me closer to my dad," Hartnagel says. "I enjoy pushing myself on those longer miles, where I have to dig deep to have faith and stay positive."

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Staying positive isn't easy, though, when one is riding the waves of grief.

"Grief is a weird thing," Hartnagel muses. "It's hard not having him around, and I often see things that remind me of him."

One thing that's helped for Hartnagel is continuing his dad's legacy with a nonprofit founded in his honor, Metastatic Mission. The organization hosts monthly marathons that take place — just like Hartnagel's run — around cancer centers in cities around the country.

"I always tell people that just because you pass doesn't mean cancer won. You win by how you live, how you never give up hope, and how even after you pass, you inspire and help others," he tells PEOPLE. "There's no doubt in my mind: My dad won against cancer."

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Read the original article on People.