Mindset is pivotal in life, you can let failures crush you and keep you down permanently or you can let them drive you. This mindset really is not hard once you see that each failure is building toward a new success. I see and hear about people being really down about an injury. But every injury tells you something new about how your body is reacting to the stress that is being placed on it. Now sometimes, in the circumstance of an injury, that event can tell you that you need to back off training a certain way, or it can tell you that more recovery time is needed. In either circumstance the injury is giving you positive feedback not only on how to train your training/recovery cycle but showing you how far your body can be pushed. In order to be your best you must always push those limits, but you must also respect those limits. There are two good indication of if you are really pushing your limits, one being PRs and two being occasional failure.
With this information do not go wild and think everyone should fail everyday, there are structure and goals needed in any successful training regime. But if you are not failing, you are not pushing hard enough. Remember, failure is not a negative thing, you must think of every fail as a “fail forward.”