

The simplest way to change your self beliefs is by repeating an Affirmation. Any positive statement can be an affirmation, but the wording of the affirmation needs to follow certain rules if it is to work well.
Affirmations can be targeted at
Who You Are
How You Behave
What You Can Do
Rules for Living
Expectations about others
Assumptions about the world
I am a loving, special, talented woman.
My name is [name], I am caring, interested in others, and people like me.
I am a do-it-now kinda guy.
Every customer is a chance for me to show my service skills.
I treat everyone I meet as a potential life long friend.
Today I will do one more thing towards getting my new house.
My past just makes me stronger.
Noticing my little daily successes shows my confidence is growing.
Thinking about the exam makes me more determined to pass.
I accept whatever life brings.
I make mistakes, but I learn from them.
I am unique and special, there has never been anyone else exactly like me, and so I welcome every day as a new beginning.
Everyone I meet has a smile for me.
There is always a way, and it is right in front of me.
The world is full of golden opportunities and helpful people.
The right phrase will bring to mind a clear image of yourself doing whatever it is you want to do and feeling good about doing it. It must make you feel good about yourself.
It must be expressed in positive terms
(not 'I will not get angry'. better: 'I am in control at all times')
It must be in the present tense
(not 'I will be confident', Better: 'I am confident') Avoid words like "can, will, should, could".
It must be about you
(not 'Robin will love me'. Better: 'I constantly find ways to make Robin happy')
It must be simple
Use your normal way of speaking and use short punchy words.
It should be concrete and specific
(not 'I want to sell more'. Better 'I know how to explain clearly how my products meet my client's needs')
It must fit your goals
To work, the affirmation must be something you actually want.
You will know when it is right because it will feel right to you.
There is nothing you can do about the past. What happened in the past is over and gone and will not change. What you can do is to change the meaning of what happened in the past. It is up to you to decide how you will allow it to affect you today.
Affirmations are about you, and only you. It is not good practice to compare yourself directly to others. Your affirmation should not be "I will sell more than Henry". That will only focus your thoughts on Henry - you need to focus on you. "I am in the top ten percent of sales people in my industry".
Affirmations are about what you want to be, what you want to do. Goals are about what you want to have, where you will end up. Affirmations are linked to goals but they are not the same as goals. You may want to earn a million dollars a year, or have a ten roomed house, or enjoy a happy family life. Those are goals. Affirmations are about you, who you are and how you think.
Affirmations are not good luck charms. They will overcome negative beliefs, but just wanting to be America's Next Top Model is not going to make it happen. Telling yourself that "I have poise, elegance and innate fashion sense" will make it possible for someone with no self belief to get started, and it will carry them through the setbacks and difficulties on the way, but success depends on action as well as wanting.
Do not talk about things you don't want. If you mention a negative thing you are automatically putting it into your mind. If you use an affirmation such as "I won't be late" your mind registers the word "late" and all its bad associations. Better to say "I am always on time."
The exact wording of an affirmation is not critical, as long as it is positive, personal, permanent and possible. You will know you have the right words when the phrase feels right for you. Change them if they don't feel right. The right phrase will bring to mind a clear image of yourself doing whatever it is you want to do and feeling good about doing it. That is the real test of an affirmation.
You cannot will yourself to be seven feet tall. But do not limit yourself as to what is possible. You may not be able to be seven feet tall, but that is no reason to not give yourself the affirmation that 'I am an outstanding basketball player'.
Six words is better than six lines.
This might all seem too easy. If it is that simple why isn't everyone a millionaire yacht owner? The sad fact is that 99.7% of the people in the world limit themselves by their own self beliefs. You can be different. Suspend your doubts, put your full mental capabilities into your affirmation, give it everything you've got. And you will be amazed by the outcome.
Every one can cook, everyone buys the same ingredients, and most people can produce eatable food. Yet a top chef can take the same ingredients in the same house and produce an unforgettable meal. The difference is that the chef cares about the quality of the outcome, refuses to accept ordinary. It's not the ingredients, it's how you think about the result.