A few weeks ago while I was out on my run, I came across another female runner who was a lot faster than me. She was on the opposite sidewalk from me, but going in the same direction. I saw her come up out of the corner of my eye and blast right by me like it wasn't a big deal. Even though I had no idea who this girl was or what kind of runner she was, I was jealous and began to doubt myself.
What if I'm not good enough?
What if I won't be able to accomplish my running goals?
Maybe I should just quit while I'm ahead.
But then I realized - I don't know who this girl is or what kind of runner she is. How she trains has no effect on how I train. Maybe she's faster than me, but can she run long distances like I can? Is she training for a marathon like I am? Is running her main fitness focus like it is mine? I'll probably never know, and once I realized that, I felt liberated and could easily focus on my own run and training.
Every runner is different. Every runner has their strengths and weaknesses. The trick is to stay focused on yourself and what you need to do in order to accomplish your goals.