When health and fitness writer, Bill Gifford turned 40, his friends sent him a message on his birthday cake.
There, written in icing, were the words: 'RIP my youth'.
"Death has always haunted us, as a species," Gifford said.
"In the old days, death came from disease or war or accidents. Now it's ageing."
So Gifford decided to study the biology of ageing.
He has written about some of the bizarre and dangerous ways we've historically tried to stop the ageing process, and the new promising science in gerontology in his book, Spring Chicken: Stay Young Forever or Die Trying.
Professor Charles Edouard Brown-Séquard is credited with the first scientific attempt to halt the ageing process. In 1889, at the age of 70, he injected himself with a mixture of mashed up testicles from young dogs and guinea pigs.
He stood before a scientific conference in Paris and proclaimed he now had the strength and energy of a much younger man.
"His colleagues were horrified. But the public went crazy over this. It became a sensation. Songs were written about the so called Séquard elixir. People all over the world were shooting up with this stuff," said Gifford.
If there was any youthful difference, it was probably the placebo effect.
Today, researchers are looking at the ageing process at the cellular level in humans and other animals.
Take, for example, the naked mole rat.
"They almost don't age at all. They don't become frail and run out of steam. They don't develop cancer. We may have a lot to learn from them."
Science continues to push the boundaries of what is possible.
British scientist Aubrey de Grey believes people can live to be a thousand years old.
According to Gifford, "we need fringe characters in science shouting about that might be possible, but that is a long way off."
"It raises questions, like, do we want to live to be 1,000 years old? Do we want other people to live to be 1,000 years old? Donald Trump comes to mind."
Gifford said there might also be as much to learn from the people who study ageing than the science itself. He spent a great deal of time with gerontologists who shared similar traits.
"As I was hanging out with these people over the years, I noticed the incremental things they did. They took the stairs, never the elevator. When we went to lunch, they ate small meals."
It is this kind of habit and choice that can carry someone into their 80s, Gifford said.
He added, "I'm reminded of that quote from the philosopher, Seneca: "Life is long if you know how to use it."