The only time in my life where I have been very thin, was when I was extremely ill. So for me thinness has always been associated with ill health.
I tend not to worry now about how much I weigh, I judge my state of health on how I feel, rather than what I look like.
My partner says that I always look my best when I am healthy, because this is when I'm most happy. He also likes the fact that I can lift heavy things :)
Overall health has a large impact on body shape, when you improve your health, your body shape will reflect this.