When you are concerned with your problems, your self is very big. When you are going about your life without thinking about anything, your self is little. If you see somebody drowning in a river and jump in to save them without thinking, you have no self at all. You are one with the drowning person.
A big self can be unwieldy. When your self is big, you have to worry about how you look, what people think of you and how you will survive in the world. You worry about success and failure. You wonder if you’re good enough. When your self is big, it interferes with your enjoyment of life.
When you notice yourself lacking enjoyment in life, pay attention to what you are thinking and see how it relates to your self. You may be judging yourself, or judging others based on your idea of your self. As you practice noticing your self growing and shrinking, your self will remain a reasonable size. From time to time it will disappear as it merges with the world around you.