Well, a feeling I've come to really enjoy is going to PT early in the morning, then coming back to my dorm, showering, and heading to my favorite on-campus dining hall and eating a really big breakfast, before going back to bed to sleep for a couple more hours.
There's that, and there's the feeling you get during a Crowning Moment of Awesome/Funny/Heartwarming (in TV Tropes parlance).
Be it a CMOH in a Pixar film, CMOA in a great game like Mass Effect, or CMOF in your favorite TV show, great stories can have a way of being life-affirming. That is one hell of a feeling.