There's a teen at work, nice guy, good attitude, good work ethic, basically a great coworker. He has this rare bone disease, something genetic, and he's not really supposed to lift heavy things.
He asked the manager to get somebody to lift something 50 pounds in weight for him. The manager told another guy to take care of this. The other guy started making catty comments about "Well I'm getting this because (first guy's name) doesn't want to." I made the observation in passing - as politely as I could stand being at the time - that the first guy has a bone disease and doesn't need to be lifting that heavy box, and the second guy shut up.
But it started me thinking. I've been upset with people sometimes when I thought they were shirking their fair share of work. Not a lot, mind you, but often enough to bug me, because I wonder how many of those people really just couldn't do what I thought they should be doing.