The police showed us pictures of dead people in car crashes when I was in high school. The purpose was to motivate us not to drink and drive. I guess they could have shown us pictures of healthy happy sober people driving along the freeway, but I doubt it would have had the same effect. Either way, there aren't a lot of dead people around to object.
Motivation can come from either direction, a mental picture of what you want, or a mental picture of what you DON'T want. The OP was merely relaying what she didn't want.
BTW, both types of motivations work for me depending on the issue at hand. As far as the weight loss part of my journey, I focus on moving towards a healthier (and healthier looking) body. As far as me no longer drinking alcohol, I focus on moving away from the picture of an abuse alcoholic. I wasn't actually abusive, I just don't want to ever become that way - its the mental picture that motivates me.
Both of my mental pictures are stereotypes, one just focuses on the negative and the other on the positive.
"It's a great life, if you don't weaken.". John Buchan