Of the primary emotions fear is the one that bears most directly on survival. Children show fear. Adults try not to maybe because it's shameful or in some circumstances dangerous. The fear response is automatic though and your body runs through its reflexes whether you want it to or not.
Your attitude is like a box of crayons that color your world. Constantly color your picture gray and your picture will always be bleak. Try adding some bright colors to the picture by including humor and your picture begins to lighten up.
