The mystery of God's will is revealed, "having made known to us the mystery of His will, according to His good pleasure which He purposed in Himself" (Ephesians 1:9). God's will is revealed in the Bible (Romans 12:2). The word of God is the will of God.
God's will is revealed as good. As a believer you can say, "Surely goodness and mercy shall follow me all the days of my life" (Psalm 23:6). Believe in God's goodness. Because God's revealed will is good, "we know that all things work together for good to those who love God, to those who are the called according to His purpose" (Romans 8:28). God's will for you is His good purpose.
God's will is revealed in Christ. God's will is love, mercy, grace, and truth in Christ. Jesus came into this world to do God the Father's will in word and deed. "How God anointed Jesus of Nazareth with the Holy Spirit and with power, who went about doing good and healing all who were oppressed by the devil, for God was with Him" (Acts 10:38). God's will for us is good in Christ.
God's will is revealed through the Holy Spirit. God's will is in the fruit of the Spirit. "But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control" (Galatians 5:22-23). That's God's good will working in you by the Holy Spirit, through faith in the Lord Jesus Christ.