Basically, Jesus said it all: when you pray, if you have
anything against anyone, FORGIVE them (Mark 11:25),
and then have FAITH that God is granting your
requests. (Forgiving others is actually only one of the
many transformations that God frequently wants us to
make before he grants our petitions.) (It's not that he's
punishing us by not granting them, but that he wants us
to learn to be better people.) (See "motivation" below.)
The Catch:
The Simple
Formula:
The problem is that both forgiving and having faith are
very hard to do. Forgiving, at least for me, usually
means I have to repeatedly let go of my anger or
resentment and then humbly ask God to replace those
feelings with good will. Similarly, keeping the faith
means I have to work continually to cultivate a faithful
mood, & while in that mood, ask God—often quite a
few times—to do whatever it is I'm asking.
Our motivation
for doing this
even though it's
hard:
It helps tremendously if we understand this truth: that
the purpose of life is to spur us to remake ourselves,
especially our attitudes, in God's image, which means
becoming more loving than we naturally are.
(Theologians call this process "sanctification.") God lets
undesirable things happen to us—I believe—in hopes of
coaxing us to choose these projects of  self-
improvement. So whenever we ask God to change
something about our lives, we can greatly increase the
chances that God will do what we're asking by
undertaking whatever bit of self-improvement the
unwanted situation was meant to coax us toward. It
may be forgiving, or it may be some other
transformation that will make us more nearly be asking
"in Jesus' name." We still have to maintain our faith, but
that's lots easier to do when we know we're becoming
the person God (who is love) wants us to become!
O
How It Works
Petitioning God: How to Get Your Prayers Answered