Chapter 11 talks about how our emotions affect our decisions and behaviors. It also mentions that we typically tend to feel the same way that our faces express. (415) In other words, if we have a sad expression on our face, we will generally feel sad. This applies for all of our other emotions as well.
There is also mention of how emotions are important, both the verbal and nonverbal ones. These expressions of emotions make it a little easier to tell if another person is lying to them.
Finally, the chapter also mentions how our emotions affect our motivation to do things. The happier a person is, the more motivated the person will be to do something that is enjoyable and vice versa.