I did have a week or so off with some pretty rubbishy flu quite a few years ago and a few days when I turned an ankle. I think the worst period for me though was in '04. Although I didn't have a huge amount of consecutive days off, I could only work when I felt well enough during a 6 month period. Some weeks that might have been as little as a couple of half days. Although I was ill, it was the side effects of the medicine that laid me up far worse. A necessary evil unfortunately. Got ditched by loads of customers even though they were aware. It did me a favour long term because much of that work was underpriced and it gave me the chance to rebuild when I was well enough.
It taught me a lot about how fickle customer "loyalty" really can be and it hardened my attitude. Can still be friendly but in a more businesslike way now.