It really annoys me when I see people attending the cardio classes in my gym who scarcely put in any effort. It's like they know they need to exercise, but aren't willing to put in the effort needed to get real results.
As another gym habitue said, if you're not going to work hard, then why bother? You're just wasting your time.
It's good to see the occasional person who really pours on the effort. There aren't many people like that. Most people need to power through with determination and really work out hard. When they are there, they help raise the energy level of the room, and they set a good example for everyone else. They're a blessing.