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 / Updated  / Source: TODAY
By Elizabeth Murray

For sisters Ilene Bryson and Jill Ryan, walking is about more than exercise. It's a way to celebrate being alive.

"When I walk, I feel I'm in control. I am dedicated and I'm committed," Bryson said. "It's about starting my day with a very clear head."

Bryson began walking as a commitment to improving her health a few years ago, and it quickly became a passion. In 2011, she completed her first half marathon. Sunday's MORE/Fitness/Shape Women's Half Marathon in New York City (part of TODAY's Run for TODAY series) will be her seventh, and in many ways her most important. It will be the first time her big sister will be there by her side.

"Doing it with her, you know, having that memory for both of us, that's a really cool thing," Ryan said.

For the sisters, finishing a half marathon is a sign of how much they've finished together. Bryson and Ryan lost their mother to cancer when she was just 51. This year, they will turn 55 and 52, respectively.

"I don't think we thought we would get past there," Ryan said, of their ages. "It's strange, it doesn't make a lot of sense, but somehow internally you just don't think you're going to get beyond where your mom goes."

Not only have they passed that mark, but they've also done it as cancer survivors. Bryson was diagnosed with thyroid cancer in 2013. Not long after her surgery to treat the cancer, Bryson got a call from her sister — she had the same diagnosis.

"We just couldn't believe that first of all, it happened to her, and second of all, it happened to me," Ryan said. "It's just so unusual."

Doctors couldn't explain the rare coincidence, but for the two sisters, what mattered wasn't so much "why" they both had cancer, but how they handled it — together.

"It meant everything," Ryan said. "I don't think I had a moment of worry or a moment of concern, just knowing that she was there. I just knew that everything would be ok."

Bryson said that she chose this Sunday's Shape Half Marathon as "another opportunity to push herself," and that she couldn't think of anyone she'd rather share the experience with than her sister, especially since this will by Ryan's first half marathon.

"The fact that we're still here, and the fact that we had this crazy thing happen to both of us and came through it, it's an amazing thing," Ryan said.