Conservative leader David Cameron has revealed he manages to cycle to work in Westminster only once a week.
David Cameron said his Wednesday cycle "gets me going"
Mr Cameron said work pressure meant he was unable to ride every day, but he cycled on Wednesdays as it "gets me going" for prime minister's questions.
And, referring to the fact that a car used to follow him with his briefcase, he stressed that he now cycles alone.
He wants more firms to consider ecological issues and said more workers would cycle if bosses provided showers.
He added: "Everybody should be thinking: 'What can I do to help with the issue of climate change?'"
The Tory leader, who has been keen to establish his green credentials, found himself accused of hypocrisy earlier this year for cycling while being followed by a car carrying his briefcase.
But in an interview on climate change for BBC Radio 1 Newsbeat, Mr Cameron said it was "not true at all" that a car followed him to work.
He said: "That did happen once or twice and I've now made sure that it will never happen again ... I have a huge amount of paperwork that I carry to work with me.
"I now make sure that when I do bicycle on a Wednesday, no car follows me. If I have papers to carry they go in a pannier on my bike and I can promise you that will never happen again."
But Mr Cameron said he was not going to give up his official chauffeur because of the number of places he had to visit and people he had to see in his job.
However, he said that he was considering the use of a hybrid car operated partly by battery and conventional engine instead of the conventional government-issued model.
In a separate interview, former Conservative leader Michael Howard has told how he predicted a decade ago that Mr Cameron would become prime minister.
Mr Cameron worked as Mr Howard's special adviser when he was home secretary in the 1990s.
Mr Howard told The Times: "I did say to people then, as his mother reminded me a few weeks ago..., that I'd told quite a lot of people that in so far as it was possible to say of anyone in their twenties - which it isn't really, because luck plays such a huge part in life - 'he is going to become prime minister', I would say it of David Cameron."