Raising money for a good cause helps bring out the playful side of people.
This certainly rings true for Princess Beatrice, her boyfriend Dave Clark and friends this week.
The Princess and her pals are coming together to run the 2010 London marathon.
As if that wasn't enough of a challenge in itself, the team will be joined together in a giant caterpillar costume as they take to the streets.
Helping to raise money for the Duchess of York's charity, Children in Crisis, Beatrice and Dave have undergone a gruelling training programme to prepare themselves.
Organisers of the run, Richard Branson's children, Sam and Holly, will donate the money they raise to Kids Company.
The team of youngsters are running for 12 different charities in total.
To sponsor the team, go to caterpillarrun.com.