Famous researchers Dr Paul Ekman and Dr Dacher Keltner had a big input into the movie. They have done a lot of work on the universality of certain emotions and how emotions are expressed in our faces, voices and touch. A certain number of emotions are expressed in the same way all over the world, with some of these represented in the Inside Out movie - joy, disgust, anger, sadness and fear.
According to Dr Ekman, each of these emotions serves a specific purpose for people. Joy is reinforcing, in that it motivates us to continue whatever we're doing so we can experience more joy. Sadness makes us ask for help; it slows us down and allows us time to find balance after a loss. Disgust allows us to avoid things that may be harmful to us. Fear alerts us to danger (fight or flight). And anger mobilizes our resources so that we can protect ourselves, and our loves ones, and it spurs us into action.
The point is that all emotions have a role in our lives and you can't impact one without impacting another. Some people don't like to feel anxious (fear), so they push it away, others won't like to feel sadness, so they bury those feelings, and so on. Unfortunately, you can't dampen one emotion without dampening down others. If you do this for a long time you dampen all emotions, including happiness. This is where I saw people being unable to feel anything, that is, they become depressed.
There were loads of awesome messages throughout the movie, and I'll finish on a couple them. You can't reframe all experiences into a positive. For instance, in the movie one of the characters lost something important to him. The emotional character "joy" tried to turn the situation into a positive, where as "sadness" hugged him and did some beautiful empathic listening. In the end, sadness saved the day, showing us that it is important to honour all of feelings, not just the nice ones.
The other thing the movie portrays well is that we experience a huge variety of emotions throughout our day, some simultaneously, with many emotions vying for our attention. We don't have to buy into each and every one of them. Accept that this is where you are at the present moment, and be mindful that various emotions are surging and dropping away throughout your day. Sometimes it is your choice which ones you grab hold of and run with.
There are loads of awesome things to learn in this movie. I recommend watching it twice, neither time with me.