You've been waiting for this day for weeks - actively preparing so that you'll be at your best when you need to perform. You've researched and rehearsed and you are ready. Until the bug hits, the one that has been going around the office or the school. You're all set and you're sick.
There are times when there is no choice. You're too sick to carry on and so you miss it. Other arrangements get made.
What I want to think about now are the majority of days, the days when you have a wicked head cold and you have to face a 2 hour commute before presenting to a room filled with important people you want to influence. You have choices. You could cancel and begin the long, hard process of preparation again. You could muddle through miserable and hope for sympathy points from your audience.
Or you could excel despite the bug. You could be so committed to your outcome that you show up fully and let go of most of the rotten feelings until after you're done.
First, you go through your rituals. By the time we are adults, we all have rituals for getting through a cold. The point is not whether they change any of the biochemistry of the cold. The point is feeling better and the rituals themselves begin to make you feel better because they are anchored to feeling better. Use them.
Second, give the voice in your head a good script. It may be telling you that "This is terrible. This always happens to me. Why can't a catch a break" etc. etc. etc. Listen the first time. You owe yourself that. Stabilize that feeling of injustice - it's part of what you need to fuel your excellence. And then tell yourself "I don't have time for this. I need every part of me to get onboard with making my performance shine today."
Now go looking for what you need to shine: the clothes, the practical stuff you need to pack, the hot shower, the works. From this point on, the way you feel is just the way you feel. It's not rotten or unfair: it's part of the toolkit that is going to get the job done. Whenever the voice in your head (or the voice of well-meaning helpers) talks up how unfair and unfortunate it all is, you listen and replace it with a thought about what you want to remember as you perform.
Even when you're feeling at your best, you need 100% outcome focus to get to your best performance. In NLP, we call it congruence.This day is no different. Stay focused and your brain will make amazing backstage arrangements to get you to your outcome.
And after it does, after you've created what you wanted to create, rest and say thank you and let yourself be fully onboard with getting better.