Sir Richard Branson determined to stay sporty

Sir Richard Branson is determined to enjoy his favourite sports into his eighties and says his philosophy in life is to "dream big".

The 62-year-old Virgin tycoon was speaking before the start this morning of the Virgin Active triathlon in London, in which more than 14,000 people will swim, cycle and run around the capital over the course of the weekend.

Sir Richard Branson and his daughter Holly (left) at today's Virgin Active London Triathlon. Credit: Sean Dempsey/PA Wire/Press Association Images

As he prepared for what is described as the largest event of its kind in the world, the billionaire said that despite what people may think about his wealth and exciting life, his health and fitness meant everything to him.

"You can have everything you possibly want but if you don't have health and fitness you don't have anything," he said.

"I'm an enormous believer in setting yourself a challenge every year and trying to accomplish that challenge.

"I'm lucky my kids are of an age when we can do wonderful challenges together."