To change a habit, make a conscious decision, then act out the new behavior.
Get yourself a goal worth working for. Better still, get yourself a project.
If you wait until circumstances justify your thinking pleasant thoughts, you are likely to wait forever.
Our self image, strongly held, essentially determines what we become.
Successful people are able to rise above crises by relaxing no matter what the external situation. Their belief in themselves, the strength of their self-image is impenetrable armor, which protects them against shattering events.
Within you, whoever you may be, regardless of how big a failure you may think yourself to be, is the ability and the power to do whatever you need to do to be happy and successful.