Light work can be defined as the ability to lift 20 pounds at a time, and the capability to lift 10 pounds frequently in an 8-hour shift. To qualify for light work, you should be able to stand up to 6 hours in an 8-hour shift.
SSA determines maximum sustained work capability using medical records and the questionnaires filled in during application. The ailments and restrictions to be considered will only be those supported by your medical records.
If it is found you are capable of handling light work, your disability application might fail to be approved when your age, work experience, education, and training are considered. The inability to perform one requirement of light work will not make you eligible for it, but you might still be considered able to perform sedentary work.