If we could be strong Christians under our own power, the Bible would have said so. Instead, it says the opposite. Consider...
a woman who was a prostitute
a tax collector who cheated people
a woman caught in adultery
a fisherman who denied knowing Jesus
a former Pharisee who kept doing what he didn't want to do
Like them, we too are weak and sinful people. Jesus never rejects us when we get off track. Instead, He freely offers us His love, grace, mercy, and forgiveness. The question always on His mind is, “How do I rescue and restore this person?”
Jesus offers us His power in the middle of our weakness. He said, "My grace is all you need, for my power is made perfect in weakness" (2 Corinthians 12:9). Jesus is uniquely attracted to help us when we're weak.