I’m ill, but I love working out. So when am I allowed to go to the gym again?

I love working out, it makes me feel good, and I like how I stay strong and look good, even though I’m getting older. But I’m ill right now, lying in my bed with a high fever and pain in my limbs, unable to do anything. It did make me wonder when I am allowed to do excersise again.
A friend of mine is a tri-athlete, at quite a high level and refered me to an excellent website.
Sportzorg.nl

It’s in Dutch, so I will give a small English summery:

1. if you have a cold, you are allowed to work out. Another way of putting it is a neck check-> anything above the neck (cold, throat pain, headache) you are allowed to work out, but less intense than usual.
2. If you have a fever, pain in the muscles, coughing, very tired, you are not allowed to work out. Another way of putting it is the neck check-> if you (also) have problems below the neck, you are not allowed to work out.

Sportzorg.nl

After a fever, recover for 2-3 days and start light.
The danger of overdoing it is, that the immune system doesn’t get enough energy to fight the desease, and it will come back or become worse.
It could take 7-15 days after a heavy fever to recover fully

A cold usually lasts 2-7 days and is no excuse not to work out.

I’m really bummed out, as I’m really heavily ill, as I was getting so strong and fit. But there is nothing else to do than recover and watch some sports on television instead...