I appreciate your response, and I'm glad it worked for you and your employers.
Kind of curious to your type of employer and the total company size. I'm in consulting, and the current company is around 20,000 people. Last company was about 100,000. People are numbers, not names, to corporate staff. At the local level, sure, they "care" about you, but as soon as you go above your own supervisor, it starts getting iffy.
Being assertive does work in certain instances but not always; I also fully admit that I could stand to be more assertive in some areas. In the "sick day/impact work" scenario, it simply won't do any good. My employer's "money's worth" of me is my time; therein lies the problem. If I tell them I won't be in because I'm sick, and I miss a deadline, I'm in big trouble. Not only me, our clients are going to hold my company responsible for this lost work. They could get extremely angry or sue, we'd lose repeat business, and everybody loses. So, if I say, I won't be in and I won't make the deadline, they'll pull me off the project and someone else will take over. I lose work.
Work = billability = job
I believe that I do excellent work, which is why I tend to get some of the harder jobs that do take more effort and longer hours to complete. But that means nothing compared to losing work for the company.