There are different body types. Maybe youre a mesomorph. He could be comparing you to an ectomorph. Look at your calf muscle (flex it). Does it end closer to your knee, or halfway to your ankle? Same test with your arm bicep, but it might be easier to see on your leg. I always say, Arnold Schwarzenegger would kill for calves like mine! Ha - makes it easier to kick this jerk to the curb. And to develop great abs. Just be your best. I tend to hurt myself too. I think its from trying to do too much too fast? Do you have a trainer? Have you tried swimming or a recumbent bike?