You choose the story.

Version A: I made the mistake of running yesterday in 90-degree heat. I kept having to stop and walk to catch my breath. I quit after a half hour.

Version B: I pushed myself to run yesterday even though it was 90-degrees outside. Though I had to take frequent breaks, I put in a solid 30 minutes.

These two (very short) stories are based on the same experience, the same set of facts. I can choose to believe Version A in which my run is a failure or I can tell myself Version B and take pride in my perseverance. 
 
The most important stories are the ones we tell ourselves about ourselves. Those stories shape how we think and feel, how we act and how others see us.
 
The next time you find yourself thinking about a personal failure, try stripping away the judgment. See if you can use the facts to build a kinder, more positive narrative. After all, it’s your life and your story – why not create the best one possible?