Wearing thin

I'm a few hours into another call and I'm exhausted.  I've started feeling sad again and am even more physically exhausted than before.  I thought about switching residencies for a while. I thought about leaving medicine as part of my future a couple of weeks ago.   I'm just so tired and feel pretty blue.  I'm on call all the time and never feel rested.  I've been getting better at my job but I think I just need time off or a different schedule, even though that's impossible.  

I'm so exhausted in every sense of the word that it erodes my hope of feeling happy and feeling better again.