God can guess better than anyone else, perhaps. But in order for you to have true free will, your decisions must remain unknown until you make them. If all your future actions are already written in stone, free will is only an illusion. At best, God can know all of your possible choices and the choice that you are most likely to make. But there always has to be a margin of error for free will to truly exist.
God is able to give you the power to endure that which cannot be changed... Why be anxious? Come what may, God is able.