As a child, you are less concerned with the future and are able to just enjoy that very moment. A child in many ways, "doesn't have a worry in the world" other than what he or she is doing right then. Children live with their emotions on their sleeve and have the ability to be fully present. They serve as a reminder to be present.
Honestly, this is really hard for me. My default is to start thinking about the future which causes me to have anxiety, fear, and can turn into control. So the first step is to just notice; where you are, what you are doing, and what you are feeling. That will then usually bring up other other emotions such as fear, anxiety, etc. If that happens, let it run its course and call somebody. Call a friend and tell them exactly what is happening. Children do this much better than we do. Watch what a child does next time a tornado warning is given. They will be afraid and will let you know but they draw near to you. That is how we are made. We need others and we need the ability to draw near to somebody else. The greatest damage we can do to our soul is when we try to do it alone.
Children bring so many gifts and one of the gifts they bring is to help us see life through the lens of a child. It is through this lens we see joy, honesty, and hope.