Casting all your care upon him; for he careth for you.
1 Peter 5:7 (KJV)
Key to surrendering all our cares to God is understanding how much He cares for us. The more we get a revelation of His perfect love, the more will we find ourselves at peace regardless of circumstances. When we receive the perfect love of Jesus we find rest in His finished works, trusting that He has already perfected all that concerns us.