I've read a lot of articles, blog posts and stories about how people know they have crossed over that line between what they were and being a runner.
Some say it's all about participating in races; for others it comes down to a desire to push yourself -- if you train to move faster or longer, no matter where you finish you are a runner; and in a recent article in Runners' World one author boiled it all down to the growth of the pile of stinky running clothes in need of a good washing.
I find all of those good indicators. For me, it also involved an evolving relationship with synthetic fibers.
Since college I've avoided non-natural fibers in my clothing. Partly this was out of being a pseudo hippie and in retrospect it also created a very convenient way of turning down clothing gifts from my mom without insulting her or letting her know that I just hated what she used to buy for me.
We did not have fancy tech clothing when I had last been a competitive runner. Now everyone was telling me that I just had to give up cotton.
Slowly I began to heed this advice. First I shed my cotton socks for fancy running socks with separate toes to prevent blisters. This is about function I told myself. Then I got some fancy shirts as race swag and realized just how much better they were for long runs.
Shorts came next. Right before my first half marathon I got my first pair of real running shorts.
The final move in this metamorphosis is about to happen. UPS is on the way with my new fancy fast drying supposedly non chafe underwear.
I look in the mirror and wonder just who this freak is that is looking back at me.
[note: between the time I wrote this and posted it, my magic underwear arrived and it is wonderful]