Supermodel and Victoria's Secret Angel Miranda Kerr, who is the global ambassador for the Earth Hour 2012, has asked people to take part in I Will If You Will Challenge to do something positive for the environment.

To show her support, the model will conduct a free yoga class for the public. An avid practitioner, Miranda has been doing yoga for many years and has even practiced during her recent pregnancy.

Currently, her challenge has been accepted and celebrities all around the world are now making their own I Will If You Will challenges to inspire people to take much needed action for the environment.

Included in this list is Transformers star and keen environmentalist Isabel Lucas who has pledged to plant 100 trees if 100 people plant one tree each.

''Earth Hour is an opportunity to come together to support a cause for the greater good of our planet and our whole human family. A moment to feel grateful for the life giving trees, the air we breathe, the food and water that nourish us and the beauty of mother nature, Lucas stated.

Style and entertainment stars Giuliana and Bill Rancic from the reality series Giuliana and Bill have promised to both go out on the town and wear Chicago Bears jerseys at their next event if 5000 people promise to take part in Earth Hour and turn off their lights at 8.30 pm March 31.

Politician Nikolay Valuev, on the other hand, has made a huge promise to organize recycling in the Duma if 100 000 people sign WWF Russia's petition on passing a new law about protection of the sea from oil spills.