"I am fortunate that I have been able to lend face value and help propagate the campaign," John told reporters at the launch of the campaign.
"When they told me, I asked them to use and abuse my image - anything that needs championing of a cause requires us (celebrities) to be there," added the actor who came dressed in a Cure t-shirt.
The actor, who recently give a hit called "Madras Cafe", added that he has learned to be a part of such causes from his parents.
"My mother takes care of children affected by cancer twice a week, feeds stray dogs twice a week and takes care of the aged twice a week," he said.
"My father is an architect and builds homes for earthquake effected people," he added.
John said he was having a busy week as he was travelling, but "sitting for something like this makes me feel special and rejuvenated".