Feeling feelings is in the moment. Right now, I'm tired, bored, a little sad. Any "thought" about one's feelings, especially those that do not belong to "now"/have passed or are about an incident other than one that is or has just happened, is dwelling.

Just like one is worrying if one is thinking about something that hasn't happened yet (no way to know if it will go well/ill or be good/bad, etc. because it hasn't happened yet, may not happen at all), we feel things all the time, as they happen, whether we realize it or not. It's all right to have "mixed" feelings (be anxious and excited at the same time or happy and sad) but one should be able to stop and think, "what am I feeling right now" and take the time to answer. There are no "right" feelings because no one else can be in our bodies having our experience so can't judge whether what we feel is right for the situation or not. Do you remember Mary Tyler Moore and the "Chuckles the Clown" episode where she was laughing at his funeral? http://en.wikipedia.org/wiki/Chuckles_Bites_the_Dust

You can't really re-feel/experience what has passed, you can remember the experience and respond to your memories of it (and perhaps remember what feelings you didn't remember feeling at the time) but other than working on a past situation in that way, usually in therapy, any other going over feelings for an extended period is probably going to be "dwelling" on them.

If someone dies, etc., yes, you are going to feel sad and angry and lots of stuff for a long time but you probably aren't going to focus (dwell) on that you are feeling those things all that time. Feelings are to help us "navigate" through our current experiences, it is information to tell us what is going on with us interiorly and exteriorly.

If someone dies and you go to the grocery store the next week and burst into tears in the canned soup aisle; it would help orient you to look around and see you are in the canned soup aisle and your childhood friend's mother use to serve you and she Campbell's Tomato soup and grilled cheese sandwiches for lunch when you were five. But it would probably be dwelling to have that happen and then cry every time you have soup, remembering that you cried for your friend and missed her in the soup aisle at the grocery store. Once you make a connection between an event and a feeling, when that connection happens again, you may acknowledge it, "Ah, it's Susie and the soup again, gee I really miss Susie and her mother and the good old days in Bethesda when we were children" but to continue thinking about it or to "get lost" in it and let your mind take you back to the good old days (when you are at work and supposed to be working) would be dwelling and inappropriate. We can't choose our thoughts and feelings but we can choose our focus and activities. Once we connect thoughts and feelings to activities in the present, we can refocus and move forward some more, get new thoughts and feelings and activities