Armstrong believes the future is bright for Team RadioShack
Lance Armstrong says he is not worried about a US federal investigation into allegations of doping as he prepares for his last international race.
The seven-time Tour de France champion is taking part in his final overseas event in the Tour Down Under, starting in south Australia on 16 January.
Former team-mate Floyd Landis has claimed Armstrong used banned drugs.
But Armstrong, who has denied any wrongdoing and never tested positive, said: "I never lose sleep."
The 39-year-old added: "It has no effect on my life. That's for other people to deal with."
The investigation is looking at whether Armstrong used government money to dope and win his seven Tours while riding with the now-disbanded US Postal team.
It follows allegations made by Landis, who was stripped of the
2006 Tour de France title
following a positive drugs test.
Armstrong insisted it would have been impossible to get away with doping over such a long time.
"They can keep looking," he added. "If you're trying to hide something, you wouldn't keep getting away with it for 10 years, nobody is that clever."
Armstrong, who now rides for his own professional outfit Team RadioShack, became a professional cyclist when he was 16-years-old and he admits that age has finally caught up with him.
"I feel all right, I can't deny my age," he said. "That is something that three years ago I perhaps thought I could deny, but I can't.
"I have never been one to sit around and reminisce much. It would be a mistake for me to think back on the stuff that I did on the bike when I have things in front of me that are much bigger than that.
"I won the Tour de France seven times and I think I won it because we changed the way people in cycling do business. And I'm not going to dance around the fact there has been plenty of questions about that.
"But the reality is we came with a whole new approach to the sport. We revolutionised the way people train, the way they build morale in the team, the way they preview the courses, the way they race, the way they sell the sport, the way they tell that story around the world.
"I leave knowing that I did my best and I don't need somebody to give me a plaque or give me a statue, it has been very good to me on a lot of levels, it has been a good ride."
Armstrong quit the sport in 2005 before returning in 2009, but in July he confirmed that 2010 would be the
last time he rode the Tour de France.
He chose the 2009 edition of the Tour Down Under to make his comeback to cycling after a two-year retirement and debuted Team Radioshack in last year's race.
Britain's Mark Cavendish will be one of the other big attractions for the event, which begins with a short street race in Adelaide on Sunday before the opening stage on Tuesday.
The HTC Highroad rider, who has won 15 stages in the Tour de France, five in the Giro d'Italia and four in the 2010 Spanish Vuelta, is taking part in his
maiden Tour Down Under.
"There's some great bike riders here. Andre [Greipel] won this race in the past," said Cavendish, who claimed that he has his sights on the sixth and final stage on Sunday, 23 January.
"We've had a look at the finale of most of the stages, and most of them are pancake flat. But I'm not here for the general classification. I'm here for a stage win. Maybe stage six."