Grey

I work at the market
and my till is not the fastest.

I go to the library sometimes

as I used to do when I was young.

I sit in the middle of the room, roughly,

and you won't spot me.

I'm usually wearing grey and my face is grey too. 

I rise my head from time to time

when I pause.

Every time I can, I go to Spanish lessons,

even when it's cold, in winter.

When I skip one, nobody notices.

This seems to be the world:

so many people outside

and that one invisible unnecessary microbe.