I had proper Flu this year, and almost exactly 4 weeks later caught COVID for the first time. Prior to these events I had a 5 year streak of being completely illness free, not a sniffle, not a head cold.
Both illnesses completely K.O.'d me. Literally 5 days straight of laying on the couch alternating between sleeping, sweating, or just groaning when I tried to move. So uncomfortable I couldn't even enjoy watching TV. I spent most of my awake time just kinda.... staring at the ceiling.
During the Flu on day 4 or 5 I was starting to feel a bit better, I was starting to care that my house was a bit of a wreck and the carpet in particular getting pretty gross (lots of dog treat crumbs). I did a half-assed job of vacuuming 2 bedrooms, the living room, and the den. Took maybe 15 minutes. That was the extent of my activity for the rest of the day, I was just wrecked. Had to sit down to catch my breath and get control of some violent shakes.
Next time I catch the flu I have to try going for a jog. It would probably put me into a coma long enough to sleep through the rest of the cold.