The next time you feel insecure or doubt your ability to handle stress of any kind imagine yourself as a five year old child and talk to yourself that way, the way you would comfort a frightened child, either in your head or out loud (if you are alone). If it helps you may want to carry a picture of yourself as a child and talk to it. Tell this inner child that you love it and that everything is going to be all right.
Think about you as the loving parent would nurture yourself as this scared, sensitive and insecure child. You might say "I know you are scared. Everyone gets scared sometimes. But it's O.K.; I'm here. I love you so very much. I'll protect you. Don't worry."
Don't just say it, feel it! Give your inner child the kind of unconditional love that a parent is supposed to give their child. Some people reserve this kind of love for their pets. Give your inner child the kind of love that accepts it just the way it is. Tell it that no matter what happens you will always love it.
If you have been angry at yourself apologize to your inner child for scaring it and explain that you just lost your temper and now you feel much better. If you have thought you were fat, ugly or unattractive in some way, apologize and tell this child that it is pretty, handsome, cute and that you love it.
You can never tell your inner child too many times that you love it; that everything is going to be all right; and that it is a very good child. Children thrive on reassurance and children of dysfunctional families, and that is unfortunately most of us, need as much reassurance and love as they can get.
It is unreasonable to expect our family, friends and the outside world to give us this kind of constant encouragement but we can and must supply it to ourselves. Little by little, you will develop more self-confidence with these self-nurturing techniques.