People will buy into something if they buy into the purpose. Having a worthy purpose is the first step to achieving great things, as an individual, and as an organization.
This suggests that true giving requires a person to act for a reason which is higher than their self-interest. Giving requires that we set aside our needs and act instead on the basis of values.
When a person is value driven in their behavior they are able to differentiate between what is expedient and what is correct in any given situation and they act on the basis of what is correct.