Mat 6:10 …your will be done, on earth as it is in heaven.
The maker of things knows better the purposes for which he made them. We were created for a purpose and Paul in Eph 1 makes it clear how we function in Him for His purposes. He uses phrases such as “IN Christ Jesus“, “IN Him” vs. 1,3,4,6,7,9,10,11,12,13,15) to show that all things work according to the counsel of His will, His purpose vs. 1,5,9,11. The Creator is also the sustainer of all, therefore the “will of God” is the rule of all His actions, and of all His acts of grace and goodness.
His will begins with His salvation meaning we “…were born, not of blood nor of the will of the flesh nor of the will of man, but of God” (John 1:13). We did not chose Him, He did. See how it is demonstrated in the call of Jeremiah, Jer 1:5 “Before I formed you in the womb I knew you, and before you were born I consecrated you; I appointed you a prophet to the nations.” Note the “I“, all God’s doing.
Your will be done is a prayer to aline ourselves with the purposes of God. To pray “God grant me the desires of my heart” means praying as David did Psa 25:4&5, “4 Show me Your ways, O Lord; Teach me Your paths. 5 Lead me in Your truth and teach me, For You are the God of my salvation On You I wait all the day”. Three key words SHOW, TEACH, LEAD. When He shows You His ways, He has your attention; when He teaches you His paths, He has your mind; and when He leads you in His truth, He has your hand. He shows that He may teach, He teaches that He may lead. This is His means of revealing His will that now becomes the desires of our hearts.