Mescalito

What do you think about dwelling on/in a particular feeling? Like when you are sad.. feeling down.. do you ever feel like you are making it longer for other reasons. Like you can change how you feel at any moment.. but regardless of the feeling being perceived as a negative one.. you want it to continue. Is that what they mean by emo? Alternatively if we are happy.. is there a problem with trying to somewhat sustain the feeling?

M