Worry?

I've always taken exception to hearing that worry is wrong. That's not to say I don't see where it comes from, I've read Matthew 6, verses 30-34:

If that is how God clothes the grass of the field, which is here today and tomorrow is thrown into the fire, will he not much more clothe you, O you of little faith? So do not worry, saying, 'What shall we eat?' or 'What shall we drink?' or 'What shall we wear?' For the pagans run after all these things, and your heavenly Father knows that you need them. But seek first his kingdom and his righteousness, and all these things will be given to you as well. Therefore do not worry about tomorrow, for tomorrow will worry about itself. Each day has enough trouble of its own.

Doesn't that seem clear? But that's not the only reason for worry. Doesn't He say He will work all things out for our good? What about the little child who goes to school a few weeks and then worries that his parents will continue to make him attend even after he tells them he hates it. It's for his good, he may be old enough to believe and almost understand that but he's still worried that it will happen.
Jesus certainly seemed worried about what was going to happen to him. He understood that it would be worth it but still worried that there would be no way out of it. He accepted it when he realized there wasn't.
What if your character needs a particular trial? Maybe my real problem is not with the word worry so much as with it not allowing for dread.