Checking In is a quick way to record precisely how you feel at any monment. When you're creating a journal entry, you can click on the Check In button to reveal a list of emotions. Just click each one that you've experienced, and try to refer to them in your journal entry.
As you check in more, you'll be building up a record of your general emotional state. You can use this information to see how things are going, and formulate ideas and plans to help you deal with those emotions. As a companion to a journal entry, a check in can really help you focus your attention on how you feel.
You might be suprised about the range of feelings that you're going through, and checking in is a great way to recognise those emotions. We can only solve problems once we know what the true nature of the problem is, and a history of check ins is a great tool to help you do that.
A significant part of knowing yourself is knowing how you react to different emotions, and that will help you to organise yourself and your life in a way that suits your personality and temperament.