Basically power through but with care and empathy for myself. Do the work, but only the important stuff, eat well, not too much and get some light movement and early sleep later.
I only call in sick if I have a fever, am contagious or am really unable to sit at a desk for more than 10 minutes due to the illness.
Otherwise I am not sick, I maybe take some pain killers, acknowledge that a) I am human b) I can always concentrate for at least 1 or 2 hours, even if I am not at my best and c) those two hours are enough for the day.
And who knows, sometimes being not at your top leads to new perspective into your work.
I only call in sick if I have a fever, am contagious or am really unable to sit at a desk for more than 10 minutes due to the illness.
Otherwise I am not sick, I maybe take some pain killers, acknowledge that a) I am human b) I can always concentrate for at least 1 or 2 hours, even if I am not at my best and c) those two hours are enough for the day.
And who knows, sometimes being not at your top leads to new perspective into your work.