When I was growing up, it was said this way: "Don't be a worry wart!!". Jesus said, "Don't worry about tomorrow. . . ." And he said, "Don't worry about your life, what you shall eat or drink, . . . " My experience tells me that this is easier said than done. Worrying seems to be a natural part of our mortal existence in a changing world.
Adam Phillips, in his book "On Kissing, Tickling and Being Bored: Psychoanalytic Essays on the Unexamined Life" writes that the word "worry" comes from a word that means to kill by strangulation. It referred to what a dog did when it caught it's prey. In some sense, that illumines the our experience of worry. We latch onto a thought or an idea and we try to consume it. We try to take it apart so we can take it into our minds and digest it.
The word has come to mean not only what we do but what is done to us. We not only worry about things, but things worry us. It is as if we are trying to simplify something enough that we can digest it and integrate it into our life, or that we are overcome by something and trying to take it apart to make sense of it.
I have never figured out how to not worry. When things happen that cause me to wonder about myself and my future, I have to spend time thinking about it. I envy those who have "worry beads" because it seems that at least the fingering of the beads gives a sense of order and sequence to thoughts that are more generally chaotic and disorganized.
So, I don't advise people not to worry. That is almost like telling people not to breathe. But, I do suggest that the unknown future and the feelings of fear that they evoke are worth pondering. I think it is human to engage in "soulful wrestling" with the principalities and powers that seem to live within us and around us. And it seems to me that this is what prayer is: soulful wrestling.
But, there needs to be margins around our worrying, our pondering. There needs to be times when we move forward in our living, not swallowed by our worries. To be consumed by worry sucks energy from living our lives and loving that which around us. Take time to pray or ponder but don't let it steal all your energy for living.