Self-talk may be very helpful if it is positive. Should your self-talk be negative, try to switch each negative word into a positive one. First you may think that this is impossible.
After a while you get comfortable with it and in the end you feel that this is quite fun. With the fun you also increase your inner strength. It is like a contest with yourself. The more you use positive words and positive self-talk the better you feel about yourself. The better you feel about yourself, the better becomes your inner strength.
You see, that this is a win-win situation where only you are the winner. This is only half-way true. Everybody around you will benefit from your increased inner strength which also means determination in what you do and what you say. Your thoughts, your deeds and your speech will then determine how you feel. And vice-versa.
Try this game and you will continue to play it until you are completely convinced and do it without even thinking that before you were harming yourself with negative self-talk.