A quicky exercise from Donald Maas
Think of a scene in a book and write down the main emotion of the main character in the scene.
(Main character probably the one most affected by the action OR the main character of the book, the one with the biggest story arc. This is from a talk he gave that I heard about. I wasn't there so this is a guess.)
think about TWO MORE emotions s/he'd be having in that scene.
write the scene with the second emotion firmly in your brain. Do this change o' pace emotion thing at least 8 times in a book.