Many things can be dealt with if we would pray preventively. Jesus taught us to pray that we would not be lead into temptation. That is preventive prayer.
This year, I began praying in advance about our reaction if we were not invited to a particular event. It was still hurtful when my suspicion that we wouldn't be invited turned out to be correct. However, I do believe that all those prayers in advance were helpful as we do not seem to have lingering resentments. I could do with praying far more of these prayers in anticipation of hardship or hurt, and perhaps this would help avoid future angry and unforgiving reactions.
Do you have any examples to share of how preventative prayer has helped you?