One problem many people have is impatience. They use their affirmations on and off for a week or two and nothing happens so they quit. It took us a long time to become the way we are. Give your affirmations at least a serious 30 day try. If what you are trying to change is a serious problem, you will probably need more than 30 days. You might even need more than affirmations to produce the changes you seek.
Affirmations are just one of the tools of change. Most of us will need more than one tool and longer than one month. Used correctly, however, affirmations are a good tool and they do help us change, grow and heal. As you use your affirmations you will become more conscious of your thoughts, feelings and behavior and you will start thinking and feeling better about yourself. As this happens, your behavior will begin to change in the direction you are trying to go. Don't give up because you are gaining greater and greater control of your thoughts, feelings and behavior.