Athletics legend Colin Jackson gave a valuable piece of advice to retired Olympic champion Liu Xiang: Enjoy retirement.

"The most important thing about retirement is to enjoy it," said the former 110m hurdles world record holder at the 100-day countdown ceremony for Beijing 2015 IAAF World Championships in the capital on Thursday.

Jackson said he enjoys his life as a TV commentator and a coach.

"I feel lucky to do many things. I guess what I like most is working with the BBC," he said.

When talking about Liu Xiang, the 2004 Olympic hurdles champion, who reportedly will host a retirement ceremony in Shanghai at the Diamond League meet, Jackson said: "Even though you are long-time retired ... you should definitely enjoy it and find something else you have passion for.

"When you are a world-class athlete, like Liu, sometimes it's difficult to find the way you want to go with your life. But if you wait and see, opportunities will become available quite quickly. And he can be just as good at whatever he chooses as he was as a hurdler."

Liu broke Jackson's world record of 12.91 seconds in 2006.

"I was happy then to see Liu break the record. And I would like to witness more at the Bird's Nest (at the world championships)," said Jackson.

Jackson said he didn't know who was the best hurdler ever.

"Not including me," he said. "When I see the different hurdlers, people from Dayron Robles from Cuba, who is a naturally gifted hurdler, to Liu Xiang, who is just flawless over the hurdles. Both of them are great, fantastic."