Human effort will give a certain amount of energy, but it is unsustainable in spiritual matters. Remember the “stony ground” and the “thorny ground” in the parable of the sower? No Fruit! Only “Holy Spirit power” is consistently sustainable.
God the Holy Spirit led Paul from the Roman province of Asia across the sea to Macedonia, where God the Holy Spirit led him to various cities for short times until leading him to remain in the strategically placed commercial city of Corinth for long-term evangelism.