Trusting in the Lord with all your heart can be a difficult task, but it's important to remember that trust is not just about the act of trusting God, it's about the condition of your heart.
Our hearts should be bigger than our minds and our understanding. If we can only trust God based on our understanding of Him, we have reduced Him to our level. This means that we believe that He is only as big as our minds can comprehend.
Growing and understanding are necessary, but they are not the end-all-be-all. As the Bible says, "In all your getting, get understanding." This means that there will always be something you don't understand.
If you are living for God, you will encounter things that are mysterious or that don't make sense. If you are the type of person who has to know everything, you will never find contentment or satisfaction. Not everything requires an answer from God.
For example, a 2-3 year old child does not understand everything, but they still trust their parents. In Luke 18:17, Jesus says that reasoning does not belong in the Kingdom of God. Trust will always require you to have some unanswered questions in your life.
Daniel 4:35 reminds us to rest in God, to get some sleep. The enemy will bring doubt, but God will never work Himself out of your life. He will always find a way to position Himself to get the glory.
There should be a place in your relationship with God where you can trust Him even when you can't track Him. There will always be things in our lives where we don't know how He will do it, but God imparts it into your heart and leaves the "how" out of it.
God is not obligated to give you all the details. He will routinely present opportunities for you to trust Him and you will be challenged.
In conclusion, Trusting in the Lord with all your heart is not just about the act of trusting God, it's about the condition of your heart. It's important to remember that our hearts should be bigger than our minds and understanding. Growing and understanding are necessary, but not the end-all-be-all. We should trust God even when we don't understand and rest in Him.