Normally, when we try to be more Christlike, we do our best to become holier; but sometimes old sins just don't go away easily, so we continue to struggle. Without genuine repentance, determination, and persistent prayer, progress can be slow. It could even go on like this the rest of our lives.
The quick and effective way is to aim for union with God. I remember once my insurance company unfairly increased my premium for an accident not due to my fault. I wrote to the chairman of the board and got the action reversed. To solve the problem, go to the top. For spiritual progress, aim for union with God. Once you surrender to God, your struggle is gone as he takes over. God now is free to transform you.
By comparison, the first approach is hard work and not always effective, while the second way is quick and certain for both you and God. This is the union advantage.