These are my favorite scriptures: Philippians 4:6, 7 says, "Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving, present your requests to God. And the peace of God, which transcends understanding, will guard your hearts and minds in Christ Jesus".
Philippians 4: 8 says, "Whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report, if there be any virtue and if there be any praise, think on these things."
Proverbs 17:22 says, "A cheerful heart is good medicine".
*Note: I try to practice Philippians 4:6,7 everyday! Instead of getting stressed and worried, I let things go and put them in God's capable hands. I have found that after doing this everyday with the little things, it is much easier to give Him the big problems that come my way! I'm so glad I am never alone! Even when it seems like I'm praying to a brick wall, I believe with all my heart that He is there and will never leave me.