Grant Hackett is known for being unbeaten in the 1500 metre race from 1996 to 2007. While he was doing all that, he was also trading shares, studying commerce & law and planning his second act.

That second act? He's now Group CEO of Generation Development Group (ASX: GDG), which he's helped grow from $694 million to $40 billion in funds under management.

We sat down with Grant for our latest In Conversation episode. He shared his childhood heroes, strange superstitions, public setbacks and the mindset that carried him from the pool to the boardroom.

Being a 1500 metre swimmer is one of the hardest distances. Did you love the grind?

I do love the grind, and any sort of success requires it, because the success is like a blip on the radar. When you win a medal or an event, that's 1% of it. The other 99% of the time you're training. And in business, you're focused on strategy, trying to execute, trying to grow the business and get the right people on the team.

I hated the early mornings though. I was up at 4:45, and it was rough after you'd done 16km the day before plus 90 minutes in the gym. But the pain? I used to welcome that. Knowing how to push through it, persevere and do it consistently was probably one of the key things that drove my career. If you want to be a 1500m freestyle swimmer, you've got to be able to put up with pain. And in business, you've got to be able to put up with pain in difficult times too. It taught me a lot of lessons I could transfer from the pool into business.

Do you think ex-professional athletes have an unfair advantage in business?

There definitely is one. You've learned all the characteristics of what it takes to be successful: discipline, teamwork, commitment, being in competitive environments and knowing how to lose and get back up, which is a really big one.
Where it's gone wrong for a few athletes is the commercial side of sport now. You can make so much money that it almost stops you from getting another skill. Look at the Wallabies pre-1995, before rugby went professional. They're all super successful: surgeons, lawyers, CEOs, business owners. You get the characteristics of high performance from being an athlete, but you have to be motivated in the next field.

Swimmers are famously superstitious. What was your weirdest ritual?
My fingernails were quite long at one meet and I cut them. Because your feel for the water is everything, I dived in, started my stroke, and felt the water run straight over my fingers. I'd lost a little bit of catch.
So I stopped cutting my fingernails three weeks out from every major meet. Just to have that little bit of extra water. Every bit counts.

So many athletes struggle after retiring. Why didn't you?

I don't think I've ever said this on a podcast before, but when I was a five-year-old I used to say I wanted to be an entrepreneur. I was probably more interested in business than I was in swimming growing up. As a teenager I was trading shares. As soon as I won prize money or got sponsorship, I was investing straight away. I studied commerce law through my swimming years, then did my MBA.

My dad always said to me: you retire to something, not from something. And it doesn't matter how successful you are financially. Do you want to sit in the exit lounge for 50 years? No thanks. Playing golf five days a week would be horrifying to me.

We also spoke about...

• Why he reckons Elon Musk deserves more credit than people give him

• His very public divorce and how it helped him become a better leader, father and partner.

• How GDG grew from $694 million to nearly $40 billion in funds under management and the three businesses driving it

• His four-part puzzle for cracking retirement income (and why most Aussies are more prepared than they think)