Heart disease, severe back pain, mental health problems, social anxiety that is severe, learning disabilities that are severe enough.
Physical pain or if you're unable to walk at all or stand for very long.
There's a whole list of medical conditions that might qualify a person for social security disability payments but the list is too long to completely write out here.
Keep in mind though that it's getting harder to actually get the disability payments approved now since so much disability fraud has been going on so even though you might have those conditions you still might not qualify for the disability payments unless the disability is severe enough.