Worry is based on our inability to know what will happen to us in a given situation. It appears to be based on reality. Humanly, how can we know what's going to happen? We don't, so we worry over the bad things that might befall us, or those we love. There is no such thing as "worrying" over the good things that might happen. We are human and thus limited in predicting outcomes. When the odds suggest a bad outcome, or we see things leading a certain direction, it's possible to get ahead of ourselves and find a certain situation frightening or unwanted. It's not always much of a mental stretch to get there.
The fact is, life is not a randomized, double-blind study. We live life with incomplete information. We make the best decisions we can, knowing they will sometimes be wrong. We see through a glass darkly.
Fortunately, God and his Holy Spirit have gone before us. He is already "there"--that time and place that we worry about. He is sovereign, regardless of our capacity to know or accept that truth. God hasn't given us the ability to know what lies ahead, but he asks that we trust him in all things. His truth and goodness prevail, regardless of how things may look to us in earthly terms. We are the creatures; he is the creator. Thanks be to God.