There's no need to beat yourself up over a "bad" run.

"Bad" runs happen, so when it does, learn from it and improve.

For myself, and what I might tell my clients, ask:

1. What went wrong?

Example: I started out too fast and didn't stick to my plan. This caused me to burnout and not be able to run like I wanted.

2. How might I execute it better?

Example: Slow down the next time. Remember to resist the urge to go faster than planned. It is tempting to take off with the crowd or to over-do it in the beginning because I'm feeling fresh.

Being mean to yourself works against you.

The next time that you are down on yourself, pause that thought process and think, so you can grow.