There are over 750 million people in the world today with some type of disability. Think about this:
The population of the state of California is 30 million people
The population of the U.S. would only equal 1/3 of the number of disabled people in the world!
In 1994-1995, the Survey of Income and Program Participation (SIPP) found that in the U.S.:
19 million people who were defined as severely disabled, did not use a wheelchair, cane, crutches, or walkers. In other words, 73% of Americans with severe disabilities do not use such devices; therefore, a disability cannot be determined solely on whether or not a person uses assistive equipment.
(McNeil Americans with Disabilities 1994-95 1997)
People with severe disabilities, who can no longer work, grieve the loss of being able to excel at their talents and utilize their gifts. I do not know anyone who would choose to be in pain, unable to do what gives them joy and have to fight for a check that is about 10%-20% of what they would be making if they could work!
It is very difficult to generalize invisible disabilities. Each person will have different causes, systems and management strategies. Some people with an invisible disability may also have a visible disability.
The more breakthroughs of modern medicine we have, the more disabled people we have. The fundamental issue is that contemporary medicine is often able to delay death but not restore health (Jeffrey Boyd, Tribute to an American Heroine, 2001). Therefore, the amount of people suffering from a debilitating illness or injury is actually rising. This leaves millions of people disabled, even though they may not appear to have any visible restrictions at all.
REMEMBER: IT ONLY TAKES ONE SECOND FOR YOU TO BECOME DISABLED!