Then I realized that it is a job. As enjoyable as the comics are to the readers, they are the artist's job. They are paid to be funny - it is just one of the requirements.
What about your job? What are you paid to do? Whatever your skill, when it is time to pull out the stops and be the skill you possess, you do it. You don't say "I just don't feel creative today," even thought sometimes that is the case. If you are a mechanical engineer, you don't say "I just don't feel very mechanical today," or, as an accountant, "I just don't much like numbers today."
You have the skills, albeit different from a cartoonist's. You draw (no pun intended) on the skills you possess and use them to power through the day. You rely on your own expertise and your past experience. That is what artists do as well.
You have to admit, however, that as much as you may not think your job is at all humorous, I am sure there are amusing things that still happen. It isn't just the cartoonist that finds the "funny" in everyday life.