I really struggled with the same problem back when I was in school and occasionally with work (although never to the point where I got fired). After everything the best thing I've learnt to do is just to push through it. Even if you hate your job, it's better to be miserable and on your feet than in bed, and it helps a bit with job stability. Some days it's just impossible, but for the most part find a way to just push through it and you'll find yourself doing better.