It takes strength to admit errors.
There is nothing courageous in hanging on fiercely to your errors. We all make mistakes but it takes strength and courage to admit them to ourselves and, even more so, to others.
If I refuse to admit my mistakes, the energy I would have spent on new projects must be bottled up on maintaining a faulty status quo.
However, once I accept my mistakes, it clears me to move forward, making sure I do not repeat my errors.