When we think about what makes us human, we think that one of the things that sets us apart is our wide range of emotions. In reality, there are only two basic human emotions fear and love. All the others are in one way or another rooted in these two:compassion, loss, sadness, joy, anger, hatred and the one today's gospel address worry. They are all just different manifestations of the same two feelings.
John captures it most succinctly when he wrote
There is no fear in love; but perfect love (teleia agape) casts out all fear (1 Jn 4:18).
When today's gospel tells us not to worry, we can make the mistake of thinking that somehow by force of will we are supposed to make ourselves stop worrying. That's foolish. No one can do that. You can't just say, "I'm not going to worry." And stop worrying.
We do know however that the human mind cannot pay attention to two thinks at the same time. We we say we are multi-tasking, what we are really doing is switching our attention back and forth between objects.
When it comes to dealing with worry this comes in very handy. If we focus our attention on the act of loving, we cannot simultaneously worry. First of all, because worry is internal, love is external. Love turns our attention outward, away from ourself, toward others and ultimately toward God.
It is simply physically impossible for me to give my full undivided attention to God or anyone else, and simultaneously worry. The brain cannot do it. The minute I begin to worry I am no longer paying attention to the other person; I have turned inward.
You say, "But what if I am sitting and talking with the person I am worried about?" Again, I would respond that if you are worrying, then you are not in the act of loving. You cannot be attentively listening, and simultaneously worrying. More than likely, while the person is talking you are thinking about what is to be done, or mustering your argument for when it's your turn to talk. That is not agape, and certainly not perfect love.
Worry, like so many of the other things we call emotions, is a child of fear. The path to overcoming it are the two great commandments. Love God; love your negherbor.
In this 21st century one of the skills we have lost is the ability to focus, to truly pay attention to one thing at a time. Our minds flit from one thing to the other constantly. When you find yourself worrying, notice where your attention is focused. Then turn it outward, toward God or some other person and love them. True love is an activity. Engage your mind in the act of loving and there will be no room for worry, or anger, or fear.