When Julie Weiss feels tired, when her feet start hurting, her body starts aching and her willpower starts fading, all she has to do to keep going is think of her father.

The Santa Monica resident runs marathon after marathon with laser-like focus and unwavering passion, raising money for pancreatic cancer research with the hope that she can help other people fight the disease that took her dad just 35 days after his diagnosis.

“Cancer does not take a day off,” she said, “so neither do I.”

Weiss, a 45-year-old real estate accountant, only uses the cliché phrase because she means it. When she crossed the finish line of the LA Marathon three years ago, she accomplished a seemingly impossible feat, completing 52 marathons in 52 weeks.

And these days, the self-described “Marathon Goddess” is preparing for another benchmark in her running career: She’ll run a 26.2-mile race for the 100th time Feb. 14 at the upcoming Skechers Performance Los Angeles Marathon, when thousands of people will traverse a course that begins at Dodger Stadium and ends in Santa Monica.

It’s all part of her ongoing fundraising campaign. Weiss is running to benefit the Los Angeles-based Hirshberg Foundation for Pancreatic Cancer Research and has secured a $25,000 match for donations leading up to the LA Marathon. Toward the end of the race, near the mile 21 marker, she’ll stop to present a check to the organization before continuing on to the finish line.

“It brings a whole new feeling when you’re running for a charity or a cause,” Weiss said.

But Weiss didn’t get into running with lofty philanthropic goals. As a 37-year-old single mother who was taking anti-depressants, she started running in 2008 as a way to improve her health.

“It was quite a transformation,” said Weiss, whose children went through the Santa Monica-Malibu school district. “I lost 35 pounds and my whole life turned around. But then it turned into this journey of love.”

Her journey took on new meaning when her father, Maurice Weiss, died in 2010. He was 75.

According to American Cancer Society estimates, nearly 49,000 people in the United States were diagnosed with pancreatic cancer last year and more than 40,500 lost their lives. A recent ACS report concludes that pancreatic cancer is expected to surpass breast cancer as the third-leading cause of cancer-related deaths in the country. The 5-year survival rate is just 8 percent.

“It’s time to shine a brighter spotlight on pancreatic cancer,” Julie Fleshman, president of the Manhattan Beach-based Pancreatic Cancer Action Network, said in a press release. “These statistics relay an even greater urgency to incite a national movement, focused on research, that will result in new treatment options and better outcomes for patients battling this disease.”

Weiss is aiding the effort by running … and running … and running some more. She’s completed every LA Marathon except one since 2008, and she logged 1,362.4 miles in official races during her 52-marathon blitz. She worked full-time that year.

“It was tough,” she said. “I’m tired. I’m really tired. … I did it because I was so passionate, and still am, about raising awareness for this disease that people don’t know about. It desperately needs funding and a cure.

“We need to keep pushing for more research to be done so we can have early detection. Usually, by the time people find out, it’s too late.”

Weiss, an ambassador for the LA Marathon, said she has created special memories each time she’s participated in the race. In 2013, she finished her stint of 52 in a year. At last year’s event, she got engaged to her coach, David Levine. And this year, she’ll hit the marathon century mark.

“It gives me motivation,” she said, “to keep doing everything I can to let people know we’re going to keep raising awareness and keep raising funds until we make a difference.”