Austin Healey, star of Strictly Come Dancing, is inviting Londoners to help brighten the capital as part of the Festive Favours campaign.
The former England rugby player is launching the London leg of the initiative by attempting to power the lights on the tree at Winter Wonderland, Hyde Park through pedal power alone.
In conjunction with vinspired.com, the youth volunteering website, Austin will be saddling up at 10:00 GMT on Tuesday December 16th and helping to brighten up London while highlighting the potency of volunteering.
"This is a great idea to get Londoners pulling together to do a fun Festive Favour," said the ex-British Lions player.
"It's a great way for people to do some good at no cost to themselves and brings it home that volunteering can be really interesting these days as opposed to the more traditional outlook that most of us think of.
"What a brilliant way to burn some calories before all the Christmas excesses while doing a favour for London!"
The aim of the London campaign is to get as many people as possible in London working together to brighten up the city this Christmas, with vinspired.com hoping to demonstrate how easy it is to make a difference to someone's day without spending any money or taking hours out of your day.
People are invited to pedal on the ten exercise bikes surrounding the tree to power the 2000 LED lights at Winter Wonderland from 10:00 GMT on Tuesday December 16th.
Local volunteers can sign up for a 15-minute session on the bikes between 10am and 10pm each day by going to vinspired.com and there will also be two hop-on hop-off bikes available to enable passers by to join in the fun and an online game which will enable people to 'virtually' cycle from their home or work computer.
The event runs until Friday 19th December.