Kriste Lewis was celebrating her 40th birthday with her husband and friends last October when she mentioned she wasn't planning on marking the milestone by doing anything exciting.
"Maybe you should try out for the Saintsations [the New Orleans Saints' cheer and dance squad]," a friend joked.
"Everyone had a good laugh," Lewis, of Hattiesburg, Mississippi, tells PEOPLE. "An NFL cheerleader at 40?"
As the laughter died down and the conversation turned to other subjects, Lewis couldn't stop thinking about trying out.
"Later that night, I thought, 'Well, why not?' " she says. "I'm a dance fitness instructor, my two sons aren't so little anymore, I have a supportive husband, and I'm strong and healthy."
She didn't even give her medical condition a passing thought. She has polycystic kidney disease which someday will shut down her kidneys, put her on dialysis and start the search for a donor.
Instead she used her disease as a motivator and, much to her surprise, made the team.
Not that it was easy. Lewis trained for six months before heading to the Saintsations' introductory clinic last April – and she almost didn't go in.
"I sat in my car for about 20 minutes," Lewis recalls, "watching the young girls go in. They were beautiful, and I thought, 'I'm 40. My time has passed. They're going to laugh at me.' "
But then, she says, "I realized I had to do it, because I had invested so much time and energy in training."
On April 30, after 200 candidates performed during three-day tryouts in front of a panel of judges, Lewis found out she made the 36-member team.
"I just stood there shaking and crying," she says. "When I called [my husband] Tim, he was so emotional that he couldn’t even speak."
Saintsations Director Lesslee Fitzmorris says it was a unanimous decision.
"She is the definition of a cheerleader," Fitzmorris tells PEOPLE. "She is actively cheering on those who share a story of overcoming adversity to achieve your goal. Her story is inspiring young and old alike."
As for her young teammates, Lewis says they regard her as sort of a big sister.
"They sometimes ask me for advice on careers or relationships," she says, "but more in a conversational way. On the flip side, they're enlightening me on everything that's trendy!"
Lewis admits she's a little nervous about her first game day on Aug. 15.
"I'm scared that I'm going to pass out!" she says with a laugh.
But she's eagerly anticipating the Saints vs. Green Bay Packers game on Oct. 26 – which just happens to be her birthday.
"When I realized that," Lewis says, "I was like, 'Holy cow. On my 41st birthday, I will have come full circle. I'll be on the field in the Superdome, livin' the dream.' "
But perhaps an even better gift has been bestowed upon Lewis by her sons Jake, 14, and Rob, 11.
"My family went with me to a recent radio interview," Lewis says, "and afterward Rob hugged my neck and said, 'Mom, you are so cool!' "