Emotional baggage was an idiom that referred to unresolved psychological trauma or past experiences that could cause ongoing emotional distress or pain.
In 2367, while giving his condolences to Beverly Crusher for her deceased husband Jack R. Crusher, Dalen Quaice said to her, "You know what the worst part of growing old is? So many of the people you've known all your life are gone and you realize you didn't take the time to appreciate them while you still could. Oh, I'm sorry. There was no reason to heap all this emotional baggage on you. I usually travel light." (TNG: "Remember Me")