If a job causes a worker serious discomfort or pain or that his/her life or health is endangered, the worker may be found to be totally disabled even if the worker is working.
A worker is not required to work if the job causes serious pain.
A worker may apply for a pension even though the worker is still working.
Often workers continue to work even though the job causes severe pain. The worker needs the income.
See Adams v. Dep't of Labor and Industries, 128 Wash 2d 224 (1995) https://law.justia.com/cases/washington/supreme-court/1995/62175-6-1.html