i am sad to say i used to be obsessed with getting down to 100 lbs. or less (I am only 5' 3/4" though..). But It would consume my thoughts to the point where I was hardly even working out at all, and just self-negating myself for not being at the weight I wanted to be, and continuing to eat unhealthy... I had gained about 10 lbs. over the winter, because, the funny thing is, I *used* to be 100 lbs. and STILL wasn't satisfied. I currently hover around 108-111 and I am a lot happier with how I look than I used to be. I learned to just not worry anymore because it was silly, wasted energy. I still work out, so I just try to judge things by how I feel, and not necessarily how I look, or the weight on the scale. My mind is much more calm about appearance, I think also in part because I eat better than I used to (try to eat 5-6x a day). However, I would still probably be upset if I got bigger than what I would think a reasonable setpoint for me would be. I don't like how I feel when I'm out of shape, and certainly don't like how I look when I'm out of shape either. I find that if I just try to work out regularly, I feel better about myself in general. So I try to just keep the negative thoughts/obsessions at bay. Right now, I weight train about once a week with a trainer, and have joined a walking group and will join a running group this weekend! I'm getting quite bored of the gym so I'm trying to socialize and get a work out at the same time by joining groups or playing tennis... Keeping active is really important to me.
thing is, i also TRY to be of the "health at every size" mindset, and fat acceptance. I've never been overweight in my life but I still think it's a cool concept to accept people of all shapes and sizes. Here is a link to a great post about the "fantasy of being thin" and how you should love yourself just the way you are...
The Fantasy of Being Thin Kate Harding’s Shapely Prose