Various physical positions for prayer are described in the New Testament.  Those who attended the Temple probably prayed standing up (Luke 18:11-13).  In Gethsemane Jesus “fell on his face and prayed” (Matthew 26:39).  Paul and the disciples in Tyre, along with their wives and children, all knelt on the beach and prayed (Acts 21:5).  The only passage which appears to prescribe a position for prayer is in 1 Timothy:

I desire then that in every place the men should pray, lifting holy hands without anger or quarrelling.                                      (1 Timothy 2:8)

Raising hands in prayer suggests asking for something and was a normal attitude for petitionary prayer in the pagan world also.  The stress however in this passage seems to be on “holy”, and “without anger or quarrelling”.  It is interesting that this passage has often been quoted with the stress on “men” while the raising of hands and “without anger or quarrelling” have been largely ignored.  In view of the trouble at Ephesus on account of which Paul wrote to Timothy, it seems likely that the stress should fall neither on “men” nor on raising hands but on the proper attitude towards others without which prayer is ineffective:

And whenever you stand praying, forgive, if you have anything against anyone;  so that your Father also who is in heaven may forgive you your trespasses.                                                                (Mark 11:25)

The physical position we adopt can vary.  What matters is our attitude before God and towards our brother or sister or neighbour.  Probably we could all improve the frequency and content of our prayers.