Any action, whether small or large, can have a profound impact on the world. Butterfly effect aside, your moods and behaviors can unknowingly spread to others (and vice versa), people's actions in life affect the genes (and thus the fates) of their children, and charities trying to achieve the same goal can be hundreds or even thousands of times more effective than others.
This life area includes understanding the many ways your actions affect the world and others around you, determining the impact you want to have and the legacy you want to leave, and how to best realize that.
