Matthew 18:19 Again I say unto you, That if two of you shall agree on earth as touching any thing that they shall ask, it shall be done for them of my Father which is in heaven.
If you look at the outside world of appearances and agree with the pain, for instance, and get someone else (such as a doctor) to agree with you, it shall be done unto you accordingly.
But if you look at the Word of God that you hear from within yourself, as Mary did, and say, as she did, Let it be done unto me according to Thy Word
(Luke 1:38), it shall be done. If another, or several others, agree with you, the manifestation may appear even more quickly. Notice that Mary went to her cousin Elizabeth after she heard the Word of the Lord to her; and Elizabeth immediately agreed that Mary would indeed bring forth the Messiah.
The choice is ours. We can agree with what we see and what others say, or we can agree with the Word of God that we are hearing from within and be in communion (in one accord) with others hearing the same Word.
We see this exemplified in the Upper Room on the Day of Pentecost. Acts 2:1 And when the day of Pentecost was fully come, they were all with one accord in one place. After the Holy Ghost was poured out on those people, including Mary, they turned the world upside down
(Acts 17:6).
We, too, can experience this turning of our world upside down as together we who know the true God and Father of our Lord Jesus Christ agree with Him and with one another that we are the city set upon a hill, a light that cannot be hid
(Matthew 5:14), the light that will bring the knowledge of God to the whole world.