As he approaches his eighth London Marathon, Jaouad Gharib, at the age of 39, has earned the right to give advice.
The Virgin London Marathon is an IAAF Gold Label Road Race.
The 2003 IAAF World champion - who on that occasion smashed the 20-year-old World Championships record - had only run one previous marathon at that point, but went onto prove his talent over the distance by becoming the second man to successfully defend his World title when winning in Helsinki two years later.
He has a marathon best of 2:05:27, set in London in 2009 when he was third, but can boast additional impressive championship performances, most notably when taking Olympic silver in Beijing 2008 after a fascinating tussle with Sammy Wanjiru that lasted until the last two kilometres.
More recently, his marathon win in Fukuoka 2010 was his first non-championships victory. So what is his secret and what keeps him motivated as he counts the days to his 40th birthday?
"As long as I'm doing well in my training I always aim to go better," said the Moroccan record holder. "I've had very good preparation for this race in the Atlas Mountains. I'm feeling very good and I hope to do better than last year.
"The same question about my age has been put to me many times. I wish I could do something about my age, but it's there. How I feel though, is very different."
And his advancing years, he believes, are actually an advantage. "Experience and training come together. Once you train, you need to use your experience to enable you to be the best you can."
You can't buy experience, however, and half marathon world record holder Zersenay Tadese of Eritrea - who enjoyed great expectation ahead of his debut marathon in London 2009 - endured a baptism of fire as he ventured out to 26.2 miles for the first time.
"For my first two marathons my body was learning the event," said Tadese; "but after two or three marathons you learn, and now I'm ok I think and training well.
"It's going to be a strong race. It's like an Olympic or World Championship here, so I've prepared well.
"This race will decide if I run the marathon or the 10,000m in the London Olympics. If I run a good time I will run the marathon."
Some five years younger than Gharib, but still technically a veteran in an increasingly young man's game, Marilson Gomes dos Santos will start on Sunday comfortable in the knowledge that his Olympic Games selection is certain, courtesy of his impressive 2:06:34 lifetime best in London last year.
It's an exceptional circumstance in another exceptional line up.
In a brilliant 2011, the 35-year-old also clocked a 10km road PB of 27:59, won the Brazilian and Pan-Am Games 10,0000m title and took the South African half marathon title.
"My PB last year in London was encouraging," he said. "I knew I had the potential to go under 2:08 and I achieved that. Now I want to improve on that again.
"London Marathon itself is an incentive to achieve more. It provides the perfect circumstances and I'm motivated to achieve a PB."
Organisers for the IAAF