Are you losing sleep over something you can't do anything about? You may be facing an illness. You can't make yourself get well. Of course, do what you can. Use common sense. But at some point, you have to turn it over to God and say, "Lord, I trust You to bring the healing. In the mean time, I'm going to enjoy my life."
Worrying doesn't help you to heal. Studies show that living stressed and uptight actually weakens the immune system. Come back to a place of peace. Or, maybe you have people in your life who are not making good decisions. You can't make people do what's right. Don't let their poor choices sour your life. You have to protect your peace. Don't go the next 20 years worried about somebody else. Turn them over to God. If you'll let go and live at rest, then God will do what you can't do. In His own way, in His own timing, He'll make things happen. As long as you're honoring God and being your best, then you can rest.
Think about this: If God isn't changing your circumstances yet, what makes you think you can change them in your own strength? Sure, we should be good examples. We should pray. But you shouldn't live stressed out over somebody else's poor choices. You have a destiny to fulfill. You need your energy, your wisdom and your creativity to become all God's created you to be.
Don't waste effort trying to change things that only God can change. Your load will get a whole lot lighter if you'll turn it over to Him and enter into His rest."Who of you by worrying can add a single hour to your life?" Luke 12:25, NIV)