Paul, Silas, and Timothy went traveling about,
“After they had come to Mysia, they tried to go into Bithynia, but the Spirit did not permit them” (Acts 16:7).
Why did the Spirit not want them to go into Bithynia? The Bible does not say. How did the Spirit keep them from going? The Bible does not say.
However, we do know that the traveling evangelistic team obeyed the Spirit and went to another place, because they did not so have it in their minds that they were going to do whatever they wanted to do regardless.
We can pray for the work that we do, and go about it with diligence, but if the Spirit does not want us to do something, He will stop us, especially if we seek to live in God’s will.