To change your self-talk, you must first become aware of what you're saying to yourself. Just being aware of your negative thoughts is the first step to changing them.
What are you saying about yourself?
What messages are you sending to your subconscious?
Once you've become aware of those things, you can begin changing those negative thoughts and beliefs to more Optimistic ones that will better serve you in life.
Negative self-talk is a habit that we have acquired over time, and it can be hard to get rid of. We tend to doubt ourselves and our abilities, and we tell ourselves that we are not good enough. It is, however, a habit that you can break. We need to stop the negative thoughts before they take root in your head. When you find yourself thinking negative thoughts, stop them mid-sentence and replace them with positive ones.
If you find that you are still having issues controlling your negative self-talk, write down the negative thoughts on a piece of paper every time they come to mind. Then, write down the positive counter-thoughts. Take your list with you wherever you go and read it as often as possible. Remember to be as kind to yourself as you would be to another person. You would never say these things to someone you love, so don't say them to yourself. If you need to, speak directly to the child you were — kindly, softly, encouragingly.