How does the show go on when you're sick?

I seriously don’t understand what’s supposed to happen when you’re sick. I always think people are either lying or pussies when they “call out sick,” because I’m of the philosophy that, no matter what, you are to fulfill your obligations.

Well, so much for that. I’ve woken up in unbearable pain today! (That time of the month.) I took Pamprin immediately and got in the shower. While in the shower, I fell out and onto the floor because I became so lightheaded from the amount of pain I am in. My boyfriend was terrified, and it was becoming obvious that I cannot go in today.

As is the case with most days, the university requires my presence today. I’m scheduled to give a brief presentation to my colleagues, and it’s been arranged for a person from another department to meet with our group to discuss data-analysis issues related to our project. He has also prepared a brief presentation and was planning to meet with our group at 11:30. Since I’m heading the project this meeting is about, it is pointless for him to come if I’m not going to be there.

I feel so defeated. I cannot believe that I am actually too sick to do what I’m supposed to do today. What’s supposed to happen in these situations? Are you supposed to go anyway and risk the chance of doubling over in pain during a presentation?

Do my colleagues think less of me because I’ve canceled my presentation and the organized meetings today?

What if your role in a day is more important than mine today, and you’re just too sick to do it? What if you’re scheduled to sing at a concert, perform a crucial surgery, or address the nation, and you just cannot do it because you feel like you’re about to give birth to alien babies? How does the show go on when you’re sick?