Having a Hard Day

For some reason, I am totally off track today.  I'm very unmotivated.  I'm craving terrible foods.  I just want to sit on the couch and do nothing.  Maybe it's exhaustion catching up to me, maybe it's stress, maybe it's hormones...the list could go on and on.  I have to remember though to not let those "reasons" turn into excuses.  {sigh} What do others do to get past those cravings?  How do you combat the exhaustion?