BOSTON -- In hindsight, Sian Pierre Regis says his mother Rebecca gave him a great childhood. In hindsight.
"Yeah, I was so mean to my mom growing up about having no money. I remember her crying a few times because I was so mean about it," he said.
Today, however, the ingrate couldn't be more grateful.
"Yeah, you realize how lucky you are and you're like, 'What was I doing? What an idiot,'" Sian Pierre said.
He says what really set him straight was a voicemail he got from his mom last summer: "I just got fired. Just want you to know that. Call me. Bye."
That was it -- short and bitter.
"I was in shock. I never expected it to happen to me. My job and my kids was my life," Rebecca said.
"So this was one thing that kept her going and I think my biggest worry was like, if she loses her job, what else does she have?" Sian Pierre said.
Rebecca Danigelis worked in housekeeping at a hotel in Boston. She was a single mom who sacrificed everything for her children. And although Sian Pierre says he didn't really appreciate that as a kid, he clearly does now.
After his mom was fired at 75, Sian Pierre started showing his gratitude in the sweetest possible way. He took her bucket list, and together they started ticking off items one by one.
Milk a cow in Vermont -- done. Take a hip hop lesson from a "Hamilton dancer" -- check. Learn to use Instagram -- getting there.
He even flew her back to her native England to throw a penny off the London Bridge and visit her sister's grave for the very first time. Many of the items on her list are things she could never do while juggling work and raising kids.
Most recently, they walked the entire length of the Boston Marathon, because after years of cleaning rooms for all those runners, she just wanted to see the course for herself.
"I never felt younger, I never felt more loved and actually I'm excited about going and seeing the next chapter," Rebecca said.
And that's how Sian Pierre thanked his mother for his thanklessness. But he says he received an even bigger gift: a lesson on love.
"You can't feel it when you're just running through life. You feel it when you help somebody up," he said.
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