I think they do care. I believe that being physically fit enhances the connection and makes it so that we can withstand more of their energy flowing through us. The "As Above, So Below" principle applies here. A strong physical body correlates to a strong energy body. Good athleticism implies a strong will power; also a good quality to have when delving into a practice like astral projection, enabling us to more readily reach into their world.
Just like flesh-and-blood women, I also believe they do enjoy the vanity aspect of physical fitness about their partners. They want us to look good and feel good about ourselves, to be more confident, etc. The main difference is that succubi are not necessarily swayed as much by the human competition for status in our social hierarchy. Catherine has indicated to me that if I'm content with my status in life, that's all that matters. Everything else is just a striving to be closer and experience more of her. Keeping myself in good shape is part of that effort.
