Dubbed the ''Happiest 5k on the Planet'', The Color Run made no misrepresentation about being a for-profit event, and an extremely popular one at that.

A sold-out event, it boasted 12,000 runners, and with entry fees at $57 per person or $52 if part of a team, the event would have brought in about $650,000 in gate takings.

With exercise endorphins and music pumping, the smiles on finishers were as bright as their head-to-toe corn starch, indicating they had got value for money in an event aiming to promote ''healthiness and happiness''.

There are considerable costs associated with running such a large event - the closure of part of Parkes Way and public liability insurance for starters, then there's a T-shirt and headband for each entrant and three tonnes of corn starch to colour the runners.

To compare, the MS Colour Dash - a copycat charity event - ran its first event in Canberra on Australia Day and charged a $50 entry fee to its 450 runners, which they made clear only covered costs. Personal fund-raising for MS Australia was encouraged on top, and raised about $57 per runner.

The Color Run also promoted a major charity partner, the Canberra Hospital Foundation, with donations totalling $33,600, or $2.80 per runner.

That includes personal fundraising by entrants through Everyday Hero amounting to $15,280, reducing the event's donation to about $1.50 per runner.

''Each event supports a local charity partner. It's not something we have to do, rather, something we choose to do,'' Graeme Hannan, managing director of The Color Run Australia. ''In addition to providing a colourful, healthy and happy event for the people of Canberra … these funds are a contribution that the Canberra community might not have received otherwise.''

Partnering with charity seems a clever marketing tactic, but it might be a necessary part of any fun run. Professor Larry Saha, a social psychologist at the Australian National University, calls charity a ''pro-social behaviour''; it's commonly taught in schools through the use of fundraising bake-offs, walk-a-thons and - more notably - fun runs.

While it can differ from culture to culture, Professor Saha agreed many of us would therefore be conditioned to associate a fun run with charity. ''If they didn't give money to charity they'd probably look greedy,'' he said.

''[A charity element] takes away from this notion that somebody's making money off the fact they're giving their energy and time to this activity … if they see some of this money is also going to charity they can use that as a justification - in addition to keeping fit and that sort of aspect to it.''

While Professor Saha said there are other social rewards which would motivate people to participate, the charity aspect is ''yet another carrot''.