How do I handle bad days? I whine, I fuss and I put one foot in front of the other and take one step at a time. Years ago I read a book and the main character was having a horrible breakdown and someone told her "you just have to get through the next five minutes. Anyone can endure anything for five minutes."
When life gets really rough I take it five minutes (sometimes one minute) at a time because there are days when looking beyond the next few minutes is just too overwhelming.