The word grudge jumps out at me in the text below:

Mark 11.25, "But when you are praying, first forgive
anyone you are holding a grudge against, so that your
Father in heaven will forgive your sins, too. "

Prayer is a great thing. I've wanted to learn more
about prayer: the why, how, when, what, who of prayer.
One thing I believe and feel sure of and that is that
prayer is a good thing. The second thing I believe is
that prayer actually shapes us toward God (not the
opposite). Although, thirdly, I believe that God
wants to and waits to partner with humans through
prayer to do things. That's mysterious

So, whatever the posture of prayer, whatever the kind
of prayer.... what if you find yourself beginning to
pray and you remember Jesus said first, before you do
all the praying, you have got to look inside yourself
and deal with grudges through forgiving. Anger,
resentments, umbrage; they've got to be dealt with!
These things are toxic.