Trusting in the Lord is commanded. To trust in the Lord is hard at first. To become totally dependent on another is not human nature. We want to be in control of our lives and be self-sustaining.
When something happens to shatter our world we often find ourselves helpless and then we reach out to God. We need to constantly be in the lord's presence and trust that no matter what happens, He is in control and wants only the best for us.
This doesn't mean nothing bad will ever happen in our lives but when it does He will be with us and is faithful to see us through.
The Lord commands us to trust Him. In Joshua 1:9 He tells Joshua "Have I not commanded you? Be strong and courageous. Do not be terrified, do not be discouraged, for the Lord your God will be with you wherever you go."
One way to trust the Lord is to pray and be in constant communication with Him.
In Philippians 4:6,7 Paul says "Do not be anxious for anything, but in everything by prayer and petition, with thanks giving, present your requests to God," and the result of this is the second part of the verse which says, "and the peace of God which transcends all understanding will guard your hearts and minds in Christ Jesus."
Proverbs 3:5,6 says, "Trust in the Lord with all your heart and lean not on your own understanding. In all your ways acknowledge Him and He will make your path straight."
An example of this from my own life is the fact that I am in constant communication with the Lord, mostly in the form of thankfulness. One day after a snow storm I was trying to drive up a steep snowy hill. My van got stuck halfway up and started sliding backward. I quickly called out to God for help. Suddenly, the van stopped and the front end started to slide sideways. I watched in awe as my front end slid all the way around until it was facing down the hill. I easily drove back down the hill and softly stopped at the bottom, thanking the Lord all the way home.
If we trust and obey Him, He is there for us when we cry out to Him and does for us what is in our best interest.