The mistakes you make present opportunities. Next time you make a mistake, instead of panicking and getting mad at yourself, try this: Ask yourself how you can turn the mistake into a positive. Trust me, you normally can. First, if there is anyone to apologize to, do it immediately and show your humanity. Experience is learning from your mistakes and I have lots of experience.
Modify the plan
Recently we messed up an email providing an offer to a subset of our customers. The response rate was way too low. One of our customers brought the problem to our attention. We worked with our vendor, fixed the email and extended the offer by two days. In the updated email, we apologized for the problem; but also let those who may have been limited by our tight deadline know that we could give them two more days.
Ask how to prevent the problem in the future
Good ideas can come out of this exercise. First, you should develop a procedure to eliminate or reduce similar errors in the future. Second, is this a problem other folks encounter too? If so, is there a product or service that would solve the problem? Perhaps, you could turn your misfortune into a business idea.
We all make mistakes and beating ourselves up serves no purpose other than to be counterproductive. I want the people on my team making mistakes. It means they are doing something.