Mistake No 1
Not seeing mistakes in their true light.
Mistakes are merely mis-takes or mis-steps. A bit like the steps of a dance, take the 3-step waltz. If you don't have that side step you sort of have just got a march. Marching can get boring. Dancing has more personality - that side step helps make dancing more than just marching. That side step also helps keep your mind focused on what you are doing and helps you get around the corners and tricky bits with more ease.
Mis-takes help your life have more personality and get you around the tricky bits. You end up learning more of what you are capable of too.
Mistake No 2
Bundling mistakes and failures together and seeing them as bad.
Mistakes and failures are actually supports to success. Without them we don't learn as much to consolidate the experience we are having and so don't take as much out of a situation we find ourselves in as we could.