Jamaica-born Johnson, who ran for Canada, will be promoting an anti-doping campaign called Pure Sport.
"Winning a gold medal and being the best in the world it cost me my reputation, my life," Johnson said Sunday.
"I'm here to try and change that. I'm trying to clear the air and clear my part of life, trying to help future generations and future athletes, athletes of my calibre, who have tested positive, been in the same boat as me, trying to help them and say, 'You're not alone'."
Johnson, who was stripped of his 1988 Olympics gold medal and world record in the 100 metres after testing positive for steroids, is hoping to convince young athletes to stay away from drugs in sports.
The highlight of the campaign called "Choose the Right Track" will be the unfolding a giant signed petition in the Olympic Stadium in Seoul Sep 24, the 25th anniversary of the race where Johnson beat American Carl Lewis.
"On the 25th anniversary of my greatest and also my worst moment in history, I'm on a mission for change.
"Athletes' perceptions need to change. The system needs to change. Sport needs to change - before it's too late," Johnson added.
--IANS (Posted on 02-09-2013)