Cleaning up your act in the sense of dealing with past negative feelings or habits. Thus it can suggest making changes in the way you go about things or present yourself.
Example: I was watching a man who insisted on living in a small stable like room that was foul with his shit and urine. He wouldn’t go out or clean it and his clothes too were filthy. He wouldn’t be helped, but blamed his condition on anything and anyone but himself. As I watched though, he came to the point of accepting responsibility for his own condition. He came out, and we then happily asked if we could put his clothes in the washing machine. He started a new life. Dennis.
Dennis had been passing through a period of recognising how fears, guilt and lack of confidence had imprisoned him. He had literally been living in this emotional ‘shit’ for years.