But that doesn't seem to apply to 65-year-old Mike Rogers, an Augusta orthodontist who finished seventh in the 65-69 age group of November's New York City Marathon. He followed that with a personal-best time of 3 hours, 28 minutes, 53 seconds at the California International Marathon in Sacramento in December.
Today, he's hoping to break 3:30 and crack the top 10 at the Boston Marathon, the world's most prestigious distance race.
Rogers said he didn't really make his breakthrough until he started training for the Augusta ESi Ironman last fall. He easily won his age group in that race, and he was more than 7 minutes faster than anyone else over age 60 in the Augusta Half Marathon.
"I'm doing about 75 miles a week now," he said. "I get up at 3:25 every day. I get up and get my run in, then I take about a 20-minute nap, then I'm ready for work."
Rogers ran his first marathon in Columbia in 1997 when his daughter, Alison Andrews, asked him to join her for the last 6 miles. Instead, he ran all 26.2 miles in more than 4 hours, and vowed never to run another marathon.
Andrews won't join him this year because she just had her fourth son, Lee Jones Andrews III. She is the reason Rogers ran Boston for the first time in 2002, the only one he has run registered as a charity runner because he didn't have a qualifying time.
After Rogers "caught the bug" at the Kiawah Island Marathon in 2001, he decided to join Andrews on the famed Boston course. He has run 37 marathons since 2001, including Boston five times.
Only one other Augusta-area runner is returning to Boston this year, but unlike Rogers, Julius Lacerna expects his second time on the renowned course to be his last.
He is more concerned with running 50 marathons in 50 states and at the age of 33, he already has 10, including one in Alaska.
Four other locals are going to be competing in the Boston Marathon for the first time.
"I've never done a marathon that big," said Mitch Musseter, who has easily the fastest qualifying time in the group, at 2:51:01.
"I've done (the Cooper River Bridge Run) once but there I kind of got out in front and was kind of alone. But I'm going to be in big packs (in Boston) so it'll be interesting."
John Head, of Aiken, and Ginger Chew, of Augusta, both agreed they're eager to see the massive crowds along the length of the race and spend some time in Boston.
Chew, who works in development for Episcopal Day School, said running has always served as an escape from the stress of work and family life, but she had never gone beyond a half-marathon before her son "shamed" her into doing a full one. After today's race, she's not sure she'll be doing any more.
That uncertainty doesn't exist for Rogers, who has plans to run another marathon this summer and already accepted his guaranteed entry for New York in November.
Rogers said he probably won't be able to train as hard in 2012, since he'll be required to travel a lot as the new president of the American Association of Orthodontics.
But even though he might finally slow down, Rogers is confident he'll be back in Boston at the age of 66.