I got a black toe nail. I kinda heard that runners get black toe nails so I did a little research of why/how.
I got a great explanation from google by Jeff Galloway. I believe he is a runner and author.
Basically it's more from the pressure underneath the toe. It makes sense because my shoes is not tight on my toes.
But what got me inspired was what he said:
"Getting your first one is a sign that you've moved your training into a higher level"
Ooohhhh cool! Haha yeah I got the toe nail when training for the 21k.
Who would've thought one could be proud of getting a black toe nail.