For those who feel fulfilled by helping others, what are some ways to make a meaningful impact?

How do you tell your child the difficult truth about a parent who has done something terrible, without shattering their world completely?
What generally causes someone to start disliking or even hating you for no apparent or obvious reason?
What lessons can we learn from situations where playing along with others' misconceptions can lead to personal gain?
Is there a reason why donating time or support to individuals feels more rewarding than giving to charity?