Hereditary is the gun, but lifestyle is the trigger.

Gail Bonner remembers hearing that line one day on television. She can’t recall the identity of the speaker, but the message resounded. She’s seen first-hand the truth of that statement.

When Bonner was a young woman, her mother died of a stroke at age 49. That death scared Bonner, who despite a healthy physique had issues with high blood pressure. Bonner, a Dallas resident, became a fitness fanatic. Still, as she watched aunts, sisters and cousins experience health problems and often die in their 50s and 60s, Bonner feared she won’t live past 50 or 60, her friend Jennifer Jones said.

Now, Bonner is approaching 70, and she plans to run in The Atlanta Journal-Constitution Peachtree Road Race on July 4, a month before her birthday and 25 years after her first race. The Peachtree is a personal goal for Bonner, but her participation represents something larger. Bonner wants to prove that anyone can live a long and healthy lifestyle.

“People have to understand that age is really just a number and you can do whatever you want to do regardless of the age as long as you prepare,” Bonner said. “So many people are amazed by how old I am it’s almost embarrassing sometimes. But to me this should be the norm and not the exception.”

After her mother’s death, Bonner started playing racquetball, took up jazzercise and started going to aerobics classes. At family reunions she worked in hotel gyms as her relatives passed by on their way to breakfast. But initially, she did little running.

About 25 years ago, a fellow IBM employee, who was 55 at the time and planned to run in the Peachtree, convinced Bonner to train with her one afternoon after work. Bonner didn’t run that day; she walked.

The next week, Bonner ran-walk, and the week after that, her third week of training, Bonner was running three miles. Later that year, at 45, Bonner ran her first Peachtree Road Race in under an hour.

“It was like a natural thing for me,” Bonner said. “I was shocked. I was like, ‘Did I actually do this?’”

After that first race, Bonner ran the Peachtree various times. She put her starting numbers on a board in her office, her friend Gladys Wright said.

Wright, who like Jones met Bonner through IBM, was impressed that Bonner found time to exercise routinely despite a hectic work schedule. While there were constantly deadlines, Bonner took advantage of the allotted two hours of exercise IBM granted its employees.

“Right after work I’d go down to the river and run,” Bonner said. “Every day. It just became such a huge part of my life.”

But Bonner hasn’t run the Peachtree in seven years. Every year, she intended to run the race but would forget to register. This year, the race took on more meaning as she neared a milestone, her 70th birthday.

While the Peachtree is a goal, running is only one part of Bonner’s exercise schedule. She does Zumba, aerobic activity and goes to boot camp. While there’s a boot camp offered for the 55-and-plus crowd, Bonner attends the more intense one and works out alongside 20 and 30-year olds.

“I call her my Tina Turner,” said Nan Searles, who runs the boot camp. “She’s eternally young.”

Bonner even played the role of boot-camp instructor with her friend Jones. Five years ago, Jones and Bonner were running and walking a trail when Jones stopped. But Bonner wouldn’t let her rest; she pushed her friend to the end.

“She said ‘you’re not quitting,’” Jones recalled. “She would not let me give up. … She’s literally pushing me, and I’m not an itty-bitty person.”

Bonner’s energy doesn’t appear to have limits. When a friend suggests walking around Stone Mountain, Bonner wants to walk up the mountain, Wright said.

Jones, Searles and Wright all said that strangers often believe Bonner is younger than 70. When people in Bonner’s age group hear she’s running in the Peachtree, they’re impressed, Searles said. But for Bonner, the decision was easy.

“I don’t feel 70,” Bonner said. “My body doesn’t feel 70. So why not?”