Cynical view of happiness.

[SteveII]

Your immediate reaction to getting punched in the face would not have bearing on your overall happiness or contentment. Being in pain has nothing to do with it. Being bitter, holding a grudge, getting revenge, etc. would all affect your overall contentment and therefore happiness.

Being in pain can definitely affect my happiness.
That makes sense in a biological evolutionary way, physical pain is your body's way of saying I'm going to send this feeling of severe discomfort to you so that you don't do that again.
I'm not saying people in pain can't laugh or be happy but it has a definite affect on your happiness without doubt.
If being in pain caused no discomfort and was easily ignored to the point of easily feeling contentment and well being while being burned that would be dangerous for the human body.

Say if you were to do a poll of the the happiness of every person who was on the rack (old english torture device) I think all of them would be unhappy, pretty much purely because of the pain of being stretched til you hear your tendons snap, or maybe it's the muscle or bone that snaps first I can't remember.

You can be in constant pain (say from an ailment) and still choose to be content and therefore happy. So I still think pain (or lack thereof) is not a component to happiness, contentment is.

EDIT: Being content about torture is unreasonable. Therefore no happiness.