Deep down we usually believe that if something is going wrong in our life, it's our fault. We are angry at ourselves for not believing we deserve better. Actually not, since of course, there is no right reason to be angry at ourselves, but often we believe that the anger will motivate us to change. Yet we see, again and again, in ourselves, in children, as well as in adults, that anger does not motivate change. It motivates rebellion, more anger, and shutting down our heart.
Anger breeds more anger, more fear, more resentment, more negativity, etc.
When a runner loses a race, there may be disappointment and maybe some anger at self for not having tried harder, but then the only way to win the next race is to leave the anger behind and just do something different that what got you to the finish line after your targeted goal. If you keep doing things the same way, you'll get the same results. So rather than being angry at yourself, do something differently that will help you attain your goal. It is the same with life. You win some, you lose some.