I also personally struggle with this, especially when I am alone and at night time. I always overthink and re-think things that I have failed with in my past and the mistakes that I have made. I too hear other people tell me that I am hard on myself, I learned that I need to accept the positive comments and believe them. Something that has helped for me is write down three positive things each day, and it helps myself keep the negative thoughts out of my mind. Hope this helps, and hope you find something that works!