@Twin Seriously, talk to me when you feel up to it. I know what that's like. Last winter I made bad grades in courses I should have pwned with ease. It's not a reflection of your capabilities, it's a reflection of the fact that you haven't been able to focus properly. When your mental state isn't the best, your performance suffers. It's normal, and you can't beat yourself up over it cos that'll only make things worse.
@Kay My job was like that for a while, and while I do agree with what Flip said, I also feel like adding that I started getting snapped at and such when I was going slower due to being sick—I got fed up of it and deliberately slowed myself down all the time. I'm now working with less than half my ass every day and the sad thing is I'm still two or three times as country fresh (by which I mean productive) as about half of my coworkers. Of course I also partly slowed down because two of my coworkers literally spend about half of their shift every shift just standing around doing nothing or sitting in the break room. They also complain about another coworker of ours who actually does her job because sometimes when it's slow she'll get out her phone.

And finally... I'm feeling tired. Lol.