A Person whose entire life is centered around physical exercise, i.e., working out. Male worker-outers (and some females, but not many) place emphasis on "bulking up" or "getting way big," and will often resort to the use of steroids to attain this. Female worker-outers tend to be obsessed with weight loss and staying thin. No matter how skinny they already are, they always seem to want to be thinner, and will constantly go to aerobic classes and starve themselves to get there. These are the people you always see at the gym, no matter what day of the week, or time you go there. Also known as a "gym rat."
"That worker-outer practically lives at the gym. He don't have a job, or go to school, or nothin' and just pumps iron all day long."