I talk with many prospective disability clients who are clearly unable to perform their past relevant work. I spoke recently with a person who had been a welder for years, but could not continue due vision and to degenerative back problems. He clearly is not going to be able to work as a welder, his sole past occupation. But that only gets you part of the way to Social Security disability benefits.
Social Security considers your ability to do “other work” at step 5 of the sequential evaluation. This includes unskilled, sedentary work. Social Security will consider your ability to do this type of work to be available if it exists in substantial numbers in several areas of the country.