So take from that what you'd like.
I've certainly started taking things a lot more seriously that's for sure.
About 3 years ago I woke up, made breakfast, sat down to eat but realised I was way too tired and needed to lay down
I went back to bed and was asleep for pretty much the next 6 days minus waking up to drink, being too hot and needing to use the bathroom
Had a dry cough to begin and severe fatigue then a fever for 2-3 days
On the fourth day I got up to pee, was going, felt light headed so I leaned on the wall then I woke up on the floor
Had passed out and fallen backwards and hit my head on the cupboard below the sink, had a sore head but luckily it was the cupboard door which had a little flex to it rather than the sink itself
After I woke up and realised where I was and what had happened I got up, felt the back back of my head which was sore but nothing catastrophic, tried to go back to bed but still felt faint so had to lean on the wall for couple more minutes before trying
On day 7 I woke up feeling 90% better, the severe fatigue had gone
I was 30 at the time, ok-ish health, well at least in terms of I didn't get sick often anyway, probably had a severe vitamin D deficiency though and was underweight
I'm sure we all have similar tales of illness, that was the worst case of flu I ever had though
I guess I say all this to say normal flu can bowl you over even if you're young and you think you're fairly healthy, but we bounce back and usually, thankfully, without medical intervention (I probably should have called 999 after passing out but all I wanted to do is go back to bed)
If you weren't worried about needing the seasonal flu jab you shouldn't be too worried about yourself and corona