Diving
Given that their job involves plunging 10 metres from a high board into a swimming pool, you would think divers would be fearless characters.
But not two-time 10m platform world champion Tom Daley.
The Briton admitted on long-running BBC radio show Desert Island Discs that he is scared witless when preparing to jump.
Daley said, "It is terrifying. When you are that high up, it feels that the diving board narrows and narrows and narrows, almost like you are on a balancing beam that you could fall off at any moment.
"There is this overwhelming feeling of adrenaline. All of your senses are completely heightened.
"It's a really weird, almost out-of-body experience to stand up there because, if you actually think about what you're doing, no sane-minded human would actually do it."
- Twice Olympic bronze medallist Tom Daley talks diving on Desert Island Discs
The show sees the guest 'cast away' on a desert island but when asked if he would be able to swim to freedom, Daley gave another surprising answer.
"I'm not that strong a swimmer. I can swim to the edge of the pool but swimming a 50-metre length, I am absolutely knackered by the end of it.
"I prefer to be out of the water and diving into it rather than swimming in it."
The 24-year-old is currently taking a break from the sport after suffering from injury and concussions earlier this year.
He plans to return next year ahead of his bid for a first Olympic gold in his fourth Games at Tokyo 2020.
Daley and his husband, Oscar-winning screenwriter Dustin Lance Black, also became parents for the first time in June.
"Feeling different"
Daley is an outspoken LGBT rights campaigner and this year called for law changes in the 70 percent of Commonwealth countries where homosexuality is illegal.
But he admits his sexuality made him feel inferior when he was young, something he has channeled in a positive way.
"It wasn't until I went to secondary school that I started to realise, 'Oh, not everyone else is like me.' And you feel 'less than'.
"I think, to this day, those feelings of feeling 'less than' and feeling different have been the real things that have given me the power and strength to be able to succeed in the other things I have done.
"You want to prove that you're not 'less than' and you want to prove that you are something and you are someone." - Tom Daley
Daley also said he was bullied after coming back from his first Olympic Games at Beijing 2008.
"I would have been 14 and I had had the most amazing experience at the Olympic Games. People didn't necessarily see eye to eye with how much I loved sport and then things started to take a bit of a turn for the worse.
"People used to call me names, I had scissors thrown at me. At lunchtime, these guys would come and rugby tackle me to the floor and think it was funny... to the point where I started getting injured.
"I just didn't feel safe anymore and I got scared and worried about going to school."
He then moved to Plymouth College which he says was "one of the best things that happened in my life".
Lessons from his father
Daley also reflected on what he learned from his father, Rob, who died of brain cancer in 2011 aged 40.
"His outlook on life and especially after his cancer diagnosis was, 'Life's short, I'm just going to live my life, be me, and I don't care what anyone else thinks of me as long as my family and friends love me.'"
After Daley won his first 10m platform world title in Rome in 2009, his father managed to sneak into his press conference.
"I don't know how security managed to allow him in but he got in pretending to be a journalist, and his question was if he could have a cuddle.
"I remember I felt like I was dying inside. I was like, 'Oh my goodness, my dad's come in, he's crying.' It was embarrassing.
"But now looking back on it, I can't even imagine what it would be like to have your son competing at such a high level, and be going through what he was going through with his health, and those lessons of not worrying about anyone else's opinion of you and just being you is something that is such a valuable lesson."