The Negative State-Relief Model is a theory that says that we help people in order to relieve our own negative feelings.
For an example, I wanted to tell a story about my neighbor. She has been diagnosed with depression. She is very serviceable and helpful with anyone in need. She is always the first to respond when there is a neighborhood “crisis” or any damage done. She always brought food for people in the ward, who were sick, just had a baby, etc. All in all, she is just very giving and thoughtful of others and their needs. However, she recently confided to my mom that the way she can relieve her depressive thoughts and feelings is through helping other people. It’s a way to channel her thoughts from herself to other people and it has been the most successful way to cope with it. This is not a bad thing, but it illustrates very clearly this theory. Because she serve and helps people to rid of already existing negative or bad feelings.
However, by the same token people who are in a good mood are said to be more willing to give. There are examples for both. It just depends on the situation.