I think that one of the important, intangible personality characteristics that a person following a diet is 1) the willingness to shop for quality food and 2) the willingness to take the time to prepare and cook the food.
The people that buy frozen meals never develop that discipline. They refuse to set aside time to prepare anything.
I bet that Arnold, Menzter, Platz, Zane, Haney, Yates ect.... Had no problem grocery shopping and cooking.
People used to complain about Jay Cutler's DVD's because he spent a lot of time cooking. I remember in one of Jay's DVDs he used a pair of heavy duty kitchen scissors to trim the excess fat of of some raw steaks. I'm glad that Jay included that segment. It was real life food prep. In the same DVD Jay cooked old fashioned oatmeal on the stovetop. He boiled water in a stainless steel pot and cooked the oats the traditional way.