It can be anything like fighting corruption or eradicating polio or even uplifting local school.
A life without a cause is pointless. This is the only way to make a better world and those things don't happen by itself. You cannot be detached from the world.
In one of my MBA class, we were asked to signup for some volunteering activity (we get credits for that). I signed up to teach 3rd grade students through Junior Achievement. That experience taught me about things outside my small world. We cannot shrink ourselves to our school-work-family-friends.