I think this is true. I feel much much better about myself when I'm the best I can be and I know I'm trying than when I let myself go, even though I might not be ugly compared to the rest of the population even when I'm fatter and doing nothing to help my appearance or posture, etc.
One thing: I have a really hard time accepting compliments when I know I'm not the best I can be. About five years ago I weighed almost 20 pounds more than I do now (not sure why really, I think I was unhappy and it was emotional eating). If I had received a compliment back then about anything--hair, clothes, "you look nice", I would have wrote it off in my mind as being untrue or as meaning very little. Now, however, I welcome compliments because I agree with them, relative to my own personal potential.