We underestimate God when we don't ask big things of Him.
Do we think He can't handle it? Do we think God really can't change that person's heart most in need of change? Do we think He can't move the mountain of hurt or resentment in our lives? Do we think He can't bring healing to our marriage?
If you don't, then we're not reading the same Bible.
Pray big. God can handle it.