'Having kids has been the biggest part of my retirement'
For many years, Sir Chris Hoy - six-time Olympic Gold medallist and 11-time world champion - was driven by winning the next gold medal in the sport he loves.
That all changed with the birth of his son, Callum, back in 2014. Callum was born 11 weeks prematurely, weighing just 2lb 2oz.
"It definitely changed my perspective. Regardless of whether you have a premature child or not, when you have children your perspective changes on everything. Things that you used to get stressed about are so irrelevant," the amiable Scot says now.
"As long as your family and kids are healthy and happy, everything else fits in around it. You used to spend time worrying how fast you could ride a bike around a track. That seems really trivial now. Winning gold medals was the most important thing in my life - and now it's not.
"Having watched Callum grow from this tiny little thing to this strong four-year-old who's running about, riding bikes, having fun, you are especially grateful for what you've got."
Edinburgh-born Hoy, 42, and his wife Sarra, a lawyer, now have two children - Callum and 18-month-old Chloe. But he will never forget those early days after his son's birth.
"It was a very difficult time," he says now. "Sarra was a bit unwell. She went for a check-up, they kept her in and then said, 'We're going to have to deliver the baby'. She was barely even showing a bump at that point, so it was pretty scary.
"Initially, he was 2lbs 2oz, a tiny little thing that you could hold in one hand. When I look at him now at bath-time, when his feet are at the taps and his head's at the far end, I remember when he used to fit into my hand.
"It's a nice end to the story for us, but not every family gets to come home with the baby."
It's clear that family has filled the void that is so often left when athletes and sportspeople retire from active competition, although Hoy has remained as busy as ever since his retirement in 2013.
He set up his bike company HOY Bikes, collaborated with charity partners and businesses and also started racing cars, entering the Le Mans 24-hour endurance race in 2016.
"I'm all or nothing, so if I do get the chance to do something, I really commit to it," he reflects. "When you retire, you no longer define yourself by what you do. You're not a champion any more. You have the memories and that's amazing, but there's definitely a period of adjustment.
"The advice that I got from people I spoke to about retirement – both sportsmen and women - was to find something you're really passionate about and get involved in it.
"The first two years were ridiculously busy, on top of becoming a dad, but I guess it's finding things you have passion for, along with perspective. For me, having kids has been the biggest part of my retirement.
"Becoming a dad keeps things in perspective and keeps you focused on the things that are important in life."
He has now written his 10th and final book in the Flying Fergus series - The Photo Finish - about the fantastical adventures of a cycling-mad nine-year-old boy, who can fly through time and space if he pedals fast enough.
"We go on tours meeting schoolkids and the whole process has been brilliant," says Hoy. "It's opened up a whole new avenue.
The father-of-two says it's important that his stories have a moral. He clearly believes hard work pays off.
"Maybe I'm just getting old and grumpy, but you watch all these talent shows on TV and there's this notion that you can have an overnight success when you discover something that you didn't know you had, whether it be amazing singing or dancing or whatever.
"The notion that the people who appear on these shows have just discovered that they can sing or that they can dance is ridiculous. Clearly they've been working hard for years at it, but the message that comes across is that we can get this overnight success and overnight recognition.
"I've been round many schools and you ask the kids in the groups, 'What do you want to be when you grow up?' Often they'll say, 'I want to be famous'. I'll say, 'That's great, what do you want to be famous for?' They shrug their shoulders and say, 'I just want to be famous'. Fame is the end goal.
"The main message I try to get across in the books is the importance of hard work. It's not all about winning the race or having success. The process of what you do, the journey you go on, and the fun you can have just doing something you love doing is a reward in itself.
"You don't have to be promised some pot of gold at the end of the rainbow. A lot of the message is about teamwork, about making do, about hard work."
Hoy, who grew up reading Roald Dahl and was inspired to cycle after seeing the film E.T., reflects that books are now a big part of his own family life at home near Manchester.
"With all the high-tech stuff there is for entertaining kids, there's nothing like sitting down after bath-time with your son or daughter and reading a story before they go to bed," he says.
He admits he's still competitive, but that his goals have changed.
"My goals now? A more balanced life. There are everyday goals and everyday challenges that aren't quite as big as becoming an Olympic champion. My philosophy is to be the best I can be."