What happens when you can't work anymore?
If you work at a company and your department is crippled because you were sick, it is a sign of bad management on their part.
The whole idea behind a corporation is to create an independent body (the corp in corporation) that does not depend on a living being. Even if an essential person is incapacitated the business should be able to continue operating. You just can't count on a human every time all the time. Although, if your absence can cripple a company it's a wonderful thing. It means you are indispensable and can negotiate to be compensated accordingly.
However, if you run your own one man operation business, it is a blunt realization. A sudden cold, a stub on the toe, or a migraine and everything changes. Human life is so fragile, at any moment we can drop dead. If you become sick to the point where you are bed ridden, your business stops. No more customer service, no more product improvement, no more business.
Healthy people are going to be disappointed when they die of good health.
As a programmer, I try to avoid dependency as much as possible. I recommend against using trendy programming frameworks, and insist on learning from scratch. I tell programmers to trust their own person. If there is one person I would like to count on, I would like that person to be me. Unfortunately, when I become sick, I can't trust myself to continue working.
It's a single point of failure. This helped me put things into perspective. If you are working on something that you think will make a difference, tell someone else about it. Get someone else motivated about it so they can join you. If you can't even get one person excited about your business that's a whole other problem in itself.
It's nice not to have to deal with others and work on something at your own pace. But if getting sick, and you will get sick, means dropping everything and possibly abandoning work, then it is time to convince others to join you.
I believe in the secret project I am currently working on. But I had to take three weeks off to take care of my health. In that time I did absolutely nothing and couldn't meet the goals that I had set. I'm gonna start looking for a motivated individual that will be willing to work with me.