My DS is 8 and money meant nothing to him because someone was always wafting it at him. However, he goes swimming twice a week (lessons) and huffed and moaned and didn't try at all; it was a mega massive trial for all concerned.
So then I star-chart-bribed him. For a good attitude and effort he gets a gold star and a pound per session. If he goes up a grade he get £20. For a poor attitude and/or effort, a red star and nowt. From the start I said it is not to be spent on sweets/cake/crisps or moshi monster cards, but we can go to a toy emporium of choice and buy anything.
It's like a different child. He's made up with himself, his teachers are thrilled, his peers amazed, he went up a grade within 3 weeks of the scheme, he counts up the money, considers what he's spending it on, does the arithmetic in his head, absolutely bob on in terms of considering finances and how soon can he do x. It's put in a money box and the stars go on the chart and when he buys something we write notes (on special paper, in special green ink pen with a nib and an ink bottle and everything Georgian and scribe-y, but only because I have them in already and he's always wanted to get his mitts on them) detailing what he had, what he's taken out and what it is for.
Anyway the point being, what has worked for us is a tie of the cash to striving, in whatever it may be, and plotting its accretion/depletion with due ceremony. The child is thrilled, I tell you.