I know this is well intentioned, but it might have the opposite effect. There has been a lot of study done on rewards and motivation. It turns out that giving external rewards can undermine motivation. For example, giving stars to children for their drawings will undermine their natural motivation to draw. The same can be said about monetary rewards. Moreover, people who do deeds for an external reward are usually less satisfied compared to those who do deeds for their own sake.

A lot of this research is done under Self-Determination Theory.