How much to do?

How much should we do to help our fellow man, our environment, future generations, etc? A complete altruist would work hard all day (at an ethical job), spend their free time working in soup kitchens or some such, never have any indulgences and give all their spare money to charity. Can you really justify going to the cinema once a month, costing ~£8, when just £2 a month can cure all sorts of ills? Well yes, in fact you can. You do. Everyone does. Even crazy hippy types have luxuries and they certainly aren't doing all that is possible to make the world a better place. So how do we do it? Perhaps this graph will help. I think the relevant variables are the impact on your quality of life (for most people £2 a month is very low impact) and guilt.

All we need now is some data, and we can start predicting how much people are prepared to do...