Many Americans are dissatisfied with how they look. They want to be thinner or have bigger muscles or have larger breasts or have fuller lips. The diet industry, the plastic surgery industry, the fitness industry all make money because people are dissatisfied with how they look. How can you be happy with your looks?
As an economist, I will explain this with mathematics.
Let the variable I be your ideal body type which is measured on a scale from 1 to 10. When I=10, this can represent the body of a supermodel of your choice.
Your current body type is measured by the variable B, also measured on a scale from 1 to 10. Let us assume that for the average person, B=5 and I=9.
Your happiness is a function of how far your body type is from your ideal body type. We can construct a utility function where happiness, H, is equal to a function of the difference between your body type and the ideal body type [i.e., H = f(-(I-B))].
There are two ways to improve your happiness. The first is to make yourself look better through diet, exercise or the extreme measure of plastic surgery. This can increase your body type factor, B, moving it closer to your ideal image, I. However, no matter how much you diet or exercise, you likely will only be able to increase your body type by one or two units. Further, as you age the level your body type will necessarily decrease. Thus, maintaining an unrealistic ideal, I, and trying to increase your body type to reach I will be a frustrating process.
The other choice you can make is to change I. If you make your ideal body very close to what your body looks like now, you will by definition be very satisfied with your body. I am not advocating that you should never exercise or eat only junk food; these behaviors will adversely affect your health. However, altering your ideal body image to be more in line with your present body type will make you happier. This is of course easier said than done (especially for many of my peers who live in Southern California). However, changing your expectations and learning to be satisfied with the body you have will make you happy.