Where the inspirational figure is selected for us, and the gap between their life and ours is too great, the effect is not one of encouragement but of disillusionment - especially if their story is told in terms of personal qualities like bravery or persistence.

BBC: Viewpoint: Do famous role models help or hinder?

Underpinning all three movements is a powerful presumption enjoying a new lease on life, that that the future is ours to create.

FORBES: What Kony 2012 Can Teach Us About Ourselves

"Many scientists and mathematicians have looked... at the question of whether life likely exists beyond Earth, and have come to the conclusion that the odds are pretty high that somewhere among the trillions and trillions of stars in the Universe there is a planet other than ours that is home to life, " he wrote.

BBC: 'No evidence' for extraterrestrials, says White House

In some cases that involves playing on their pity -- and on ours, too, as the filmmakers imply that her weight is a symptom of her unhappy life.

CNN: Review: Melissa McCarthy steals 'Identity Thief'