1. My sin is always a lot worse than I think. If I doubt that I just need to look at the Cross and think more about Hell.
2. God's grace is always far more wonderful than I think. If I doubt that I just need to see all that I have "in Christ" and understand more about the new heavens/earth.
3. My death and the future world are coming are far sooner than I think. I need to ask myself at the end of every day "how will this day look on the Day of Christ?"
4. The Holy Spirit can do far more in me and through me and I have ever envisaged. Am I trusting His power or my willpower?