Jaquta is exactly correct....you have to get to the other stuff, get your life moving, and substitute healthy action for daydreaming.
You may like to check out the doctor's comments to some questions about concentration dating back to November 7 2009. One is entitled, 'concentration' the other 'what do i do'.
Basically they just say that there is other stuff on your mind.
Stressing about stuff can also be exhausting.