it is possible to work sick

You should only be doing that if you're contagious but otherwise capable of working. If you're sick sick then take a sickie and go to bed.

a positive voice in their head that supports and encourages them to be their best

Me I have one. It's very snarky though so maybe it doesn't count? XD

Scaling back efforts a bit isn't giving up, you're just being mindful of your energy levels and looking long term now.