Six-time Olympic sprint champion Usain Bolt wants to help restore faith in the sport after failed drug tests by fellow Jamaican athletes.
Asafa Powell and Sherone Simpson recently tested positive, as did American Tyson Gay, the fastest man in the world this year.
Bolt, 26, runs at the London Anniversary Games at the Olympic Stadium at the weekend.
"I have to work even harder to help the country and the sport," he said.
"Now I'm even more focussed and ready to go and do better and try to inspire people and to show people that it is possible."
Bolt insists he has never taken drugs and said: "I'm clean but you have to be very careful as an athlete because right now there are a lot of things on the banned list.
"You have to keep up to date with this kind of thing. It's kind of hard, but that's why you have a team to make sure.
"I get tested all the while. I got tested the day before yesterday. It's just part of the routine. "
Bolt, the 100m and 200m world record-holder, pointed to his success as a junior athlete as evidence of his innocence.
"I've broken every record there ever was to break since I was growing up," he told the BBC.
"It's not a surprise that I'm breaking world records because I've been doing it since I was a junior.
"I want to explain to people that 'this is just me'. I run fast because I have a talent and was put on this Earth to inspire a lot of people."
The US Anti-Doping Agency informed American Gay, 30, that his A sample from an out-of-competition test in May was positive.
Powell, the all-time fourth quickest, tested positive for a banned stimulant at June's Jamaican Championships and fellow Jamaican Simpson failed a drug test at the same event.
After Powell tested positive for the banned stimulant oxilofrine at the national trials last month, Bolt said it was a blow for Jamaica and athletics.
"I didn't want to bombard him with questions," said Bolt, who will run the 100m and 4x100m at the London Anniversary Games.
"I told him, 'Sorry to hear what was going on.' And he said, 'Yes, it's kind of rough, it's hard."'
With Gay and Powell still waiting for the results of their 'B' samples, Bolt was keen to avoid speculation when he spoke to the media in London on Thursday.
"There are a lot of details left to be discussed," he said.
The recent spate of positive drug tests has put the focus back on a sport that has been dogged by doping scandals in the past.
"It's going to set athletics back a little bit, but as a person I can't really focus on this," added Bolt.
"I still have the World Championships, everyone is stepping up their game, so I have to really focus on that.
"I am just trying to work hard, run fast and hopefully help people forget what has happened and just move on."
Bolt was speaking on the same day a Jamaica football player tested positive for a banned substance after a World Cup qualifying match against Honduras.
The Jamaica Football Federation said it was notified by Fifa that a "member of the Jamaican squad returned an adverse analytical finding on his urine sample" after the 11 June game.
Bolt became the first athlete to retain the Olympic 100m and 200m crowns when he took gold in both events at the 2012 London Olympics last summer. He then won his third gold of the Games when he anchored Jamaica's sprint relay team to a world record.