You bounce into the gym fresh full of energy and enthusiasm for your fitness workout. Your first station is the cross trainer. You jump on, set the resistance at a reasonable 10 (out of 16 which would be almost impossible) and you start pumping your legs firing at about 160-170 strides a minute. A fair whack!
You look over to the machine next to you and the guy on there is sweating buckets and trundling along at sedate pace. You glance at the display on his machine and he's only been going 10 minutes and he's just managing 120-125 strides a minute. You congratulate yourself on your efforts and think to yourself that maybe the guy next to you is not really cut out to be in the gym. He cannot cope with making the effort needed to really get fit. You turn on your music and get into your routine.
Ten minutes later and the chap on the other machine finally gives up, bathed in sweat. He's done 20 minutes which is reasonable but now he is going for a shower. It is then that you look over and see that the resistance setting on his machine was 15. You had not been able to see that before and you suddenly understand why he was only managing 120 strides a minute.
As he leaves you overhear the conversation he has with the gym manager. "Good workout?"
"Yes thanks, but that last station is a killer after you've done 20 minutes each on the first three".
The moral is do not judge when you see what seems to be someone who is not performing or up to the task. You have no idea of the trials they have been through nor the challenges they face that you cannot see.