When you spend half an hour looking for your glasses before you realize you're wearing them.

When you notice there's a new building on the route you take to school every morning...except it's not new, it's been there for a year.

When you walk right into the metal door...thingy that's between the doors at school even though you're pretty much looking right at it.

When you fall down the same set of stairs twice in one week.

When you walk up some stairs, and somehow you still don't notice a step in the middle of said staircase, trip and nearly brain yourself on it.

When you crash your bike into a trashcan that was in plain sight, and you noticed a long time ago.

That should do for now.