Excuses are specific kind of dis-empowering beliefs. They have  a logical component, which is often may be described as a rationalization. There is always a very strong self-preservation and self-defense emotional component responsible for the belief creation and role.

Example:

I can not lose weight because my metabolism is too slow.

Emotional component.  What is a role of this belief in our mental structure of thoughts and ideas? It provides us with a comfort thought that our weight management failures are result of something that is not under our control. It provides us with a reassurance that we are in charge, in control. And, of course, we have a perfect rationalization to support this theory.

How does it help us? Destroying such excuses is an extremely powerful step. It helps to create a reason for a new motivation. It forces us to be out of balance, destroys our comforting thoughts, forces us to look for new solutions to achieve a new balance. A new belief formation as a result of excuse destruction usually helps us to deal with the problem more constructively.

Make sure to test a new belief for efficiency. If your new belief instead of "My metabolism is too slow" to be replaced by something like "I am genetically predisposed to be overweight". Would it help you.

Also, make sure to check the new belief for safety. What about a new belief like "I can not lose weight because I do not smoke". Is it safe?