I'm a daily runner and I had influenza in February, for the first time in 30 years. I had a high fever for a full week and could not even sit up in bed.

People tend to think any bad cold is the flu, and underestimate just how bad actual influenza is. In retrospect, the narrative of "COVID is just like a bad flu" is pretty accurate, because the actual flu is a pretty traumatic experience, and the idea of getting a worse version is terrifying.

Also a daily runner (6.5 years) - the worst time to run is when you have a head cold. The impact from the run just pounds throughout your skull. I have run when I had influenza and Covid. Only one mile at a time, up and down my driveway, but it wasn’t pleasant. But it was really only bad for a day or two, and for the sake of the running streak, you run (jog/walk) your mile and you’re done (and you collapse back to sleep). Then, once you’re starting to feel a little better, the feeling of running just one mile (when you’re used to running 3 or more) is the hard part.

I also ended up training for a marathon while I had a mild pneumonia. I had no clue until I saw my doctor for a routine checkup.

When you have a running streak like this, you find ways to make it work. You’re often running with some kind of a knock, be it a cold, or some knee pain.

I am a runner. I had proper flu this year for the first time. I have never been that ill ever before. I could not even get upstairs to bed one night when I was at my worst.

My flus were probably covids, I think it tends to bounce around in the population in the post covid days while loosing strength.

I have one really bad case if flu 20 years ago. Maybe I'll have to give up my streak then. It will be a bit sad, but maybe good for me that it opens up for some other way of exercise.

Different people react differently to flu and colds.

I usually don’t get any colds at all, but I catch the flu once a year and need to be in bed at least for a week. So I started vaccinating since a couple of years and have avoided it so far.

My wife on the other hand catches every cold possible but her flu is gone in a couple of days.

Said that, my doctor has always strongly advised against doing any sport during flu or immediately after due to risks of heart infection. That’s something I’m going to follow, I’m not a sports professional and I have no need to risk my hearts health.

I ran a couple miles on a treadmill the last time I had COVID because I was going stir crazy from lying on the couch all week. It actually gave me a bit of a boost for the rest of the day, though I returned to feeling crappy the following day.

Yes, that mistake is common in English as well.

Different people react differently to flu and different strains are different. I remember when I was 30 I got the flu and I had enough energy to walk to the nearest convenience store to get lunch and enough energy to do an hour of driving practice a day and the rest of the time I lay in bed. I did not have the energy to read a book. I didn’t have the motivation to turn on the radio. It was awful. Glad I haven’t had the flu since.

I think part of it is that I just don't think of pain as per se bad. A lot of people I know who struggle with exercise feel a little discomfort and act like its the end of the world. They get shin splits or something and they decide they can't run. I've had mild shin splits continuously for 15 years. It doesn't really bother me in the same way, I guess. When I get back from a run if I lightly bump my shins its excruciating.

I will say that now that I am getting older its getting a bit tougher - the pain is worse and lasts longer and real chronic pain kind of bums me out, but I just enjoy the challenge of trying to work around my body.

They might be unpleasant but still fun. And they may be painful but in reward you get to see places you would otherwise not. Or you may get to discover your limits, which are of course further out than just pain and discomfort. So there is absolutely enjoyment in these "unfun" things.

Plus of course the chance to humble brag online afterwards!

Just because you feel like shit and your head is saying "this sucks ass", there's also the endorphins being released, the feeling of achieving something, of overcoming your own limitations and stuff.

I mean it's not for me but I can see how in hindsight (it's always in hindsight, never in the moment) it'll be considered fun. Or at the very least a story to share with friends or the internet, which is also fun.

I barely felt covid, if not for temporary loss of smell I wouldn't think it was anything more than a moderate cold.

Lymphatic system is actuated by your movement. Sure, it will work with just the little movements that your body does to keep in one piece, but for full performance so to speak you need to move around.

Depends how sick, I have frequently heard that with mild head cold, that has not gone to lungs it is good to run to activate immune system etc.