If you are trying to change something about yourself, you are probably going down the motivation path. You are subjecting yourself to good, positive thoughts in hopes that it will instill in you a sense of purpose and the will to begin the process.
The reason that goes wrong is that change does not come from happiness. Think about it. If you are happy, there is no reason for you to change that state of affairs. Your reasons for wanting change come from unhappiness. To go from wanting change to actually changing, you need to amplify that unhappiness, not assuage it with happy thoughts and feel-good psychological trickery.
You will change when your current conditions fill you with so much disgust that you run away from them. So much disgust that you will crawl if your legs fail you. Such overpowering disgust that you cannot bear to stand not changing for even a moment more.