In Central State Hosp. v. James, 147 Ga. App. 308, 309-310 (1) (248 SE2d 678) (1978), the Court distinguished between those disabilities resulting from a change in condition and those resulting from a new accident. When a claimant sustains an injury, is awarded compensation, returns to his normal and ordinary job duties, but then as a result of the wear and tear of ordinary life and the activity connected with performing his normal duties, his condition gradually deteriorates to where he cannot continue to perform his ordinary work, such facts constitute a change in condition and not a new accident. On the other hand, when a claimant is injured on the job but continues, without an agreement or award, to perform the duties of his employment until forced to cease work because of a gradual worsening of his condition that is at least partly attributable to his physical activity in continuing to work, such facts constitute a new accident. A new accident may result either from a gradual worsening of a pre-existing injury due to aggravation by work duties or from the occurrence of a specific job-related incident.