So why do we do it? The answer lies in our temporal perspective.
For example, suppose that you are worried about losing your job. You have a bad boss that apparently has it in for you. With a family to support, bills to pay, and very little money in the bank, losing your job is a very scary thing. So, you worry. Day and night, this worry consumes you.
Let's assume you are a Christian. You take your worries to God on a daily basis through prayer. You pray that God might spare you of this job loss. Every single day, you repeat this prayer. But the prayer is born from your worry.
You lose your job. Your worst fear is realized. You are unemployed with mouths to feed and bills to pay. You wonder, "Where was God when I needed Him? Why didn't He answer my prayer?"
Two weeks later, an old friend calls you and tells you he is looking for someone just like you for an incredible job opportunity with his very successful business. The job pays double what you were making previously. The idea of working for your friend thrills you because he is a great guy.
When you worried, God was there. He heard your prayer. You just couldn't see the big picture. Your perspective was short-term; getting through the next day, while hopefully remaining employed. However, in hindsight, it's all very clear now. You are much better off than you ever dreamed you would be. You prayed to keep your job. God had something even better in mind for you.
That sums up the problem with worry. Our perspective is short-term and earth-bound. God's perspective is eternal. He doesn't really deal in short-term setbacks. He deals in the ultimate goal- to get you to Heaven, for all of eternity.
When you look at it this way, pretty much every problem seems inconsequential. Against the timeline of eternity, your short-term problem, whatever it is, isn't worth the worry.
It's the way God planned it.
You have a choice. Submit to God's plan. Give it to Him. Or not. Keep worrying about it.
Either way, the end result is going to be the same. . .