As if it's already given

The modern text on this site says: believe that you have received it. Past tense, as if it has already happened. That is how the oldest manuscripts read. The King James Version follows later manuscripts: believe that ye receive them.

It isn't a trick to force God's hand. It is trusting that God has already heard, before you see anything happen. Whoever prays like this prays not with a clenched fist but with open hands. That way you also learn to accept what God gives, even when it's different from what you asked for.