Disability means inability to engage in any SGA by reason of any medically determinable
physical and/or mental impairment which can be expected to result in death, or has
lasted or can be expected to last for a continuous period of not less than 12 months.
To meet the definition of disability, an individual must have a physical or mental
impairment or impairments of such severity that the individual is not only unable
to do his or her previous work but cannot, considering his or her age, education,
and work experience, engage in any other kind of substantial gainful work which exists
in the national economy.