Notice whatever you notice. Be it emotional or Physical. The Idea is to go into the feeling and experience it fully. So it's a challenge when you've already labled it, pain, good, bad, angry, happy, etc.
I found it easiest to get into the feeling exercise by asking the questions, If this feeling was a colour what colour would it be, If it had a shape what shape would it take on, if it had a texture what texture would it be, if it had a sound what sound would it make, if it had a taste what would it taste like, if it has a size what sized or type of container would I need to put it in? That way I avoid judging or labeling the feeling but experience it.
Alex