Why should we tell God what He already knows?

Les teaches that God invites His people to bring even their little problems to Him; He does want to be bothered, if that is the word to use. In everything, by prayer and supplication with thanksgiving, we are to make our requests known. Les explains that asking and asking without thanksgiving is not effective, but asking with thanksgiving—realizing God does not have to do what we ask—He will answer according to His grace and mercy. He says to thank Him ahead of time for what He will do with the particular request. Paul says basically the same thing in Thessalonians: make supplications with thanksgiving and let requests be made known to God. God surely knows, but He wants us to communicate; He wants us to tell Him from our heart what we desire and need, even though He already knows. Les notes that someone asked why pray if God is sovereign, knows everything, and His will will be accomplished anyway; it took him a week to find the answer.