You can't make people change, but the organizers of WorldFest hope that people consider being vegetarian for both moral and health reasons.

This quote means that it is not possible to force people to become vegetarian, however the people organizing WorldFest hope that people think about the potential benefits to both their health and their conscience if they choose to become vegetarian. Worldfest is an event which encourages vegetarianism and can provide people with information on the moral and health implications of the lifestyle.