I relate wholeheartedly, my dear. I am nowhere near as in shape as I would like to be, but having fought this particular self-image bugbear for years, let me give you some advice.
First, choose your role models carefully. Christina Ricci needs to eat a sammich. Or two, or three. Our culture has held up images of women who are seen as "healthy and toned" when really they're anorexic and not at all healthy. I'd be willing to guess that half of Hollywood is so thin they no longer menstruate. Our standards have become so skewed that we have forgotten what a normal, healthy female body really looks like. If you must compare yourself to someone, why not to Kate Winslet, or Liv Tyler, or some other woman who looks beautiful and refuses to cave to the Sharpened Clavicle aesthetic?
Or better yet, why compare yourself at all? Now, as many here *cough*Jess*cough* will tell you, I am the worst follower of this advice. But that doesn't mean it's not good advice to begin with. Your body is yours. You have your own bone structure, genetic distribution of fat, metabolism, skin tone, yadda yadda yadda. It's going to look the way it looks, and there's not much you can do about it besides help it be the best version of itself that it can be. And don't compare yourself now to yourself 5 or 10 years ago. Body chemistry changes. Body structure changes. There's no getting around it. We are all going to expand, contract, sag, wrinkle, bloat, and eventually die. Even Christina Ricci, except for the parts of her that are non-organic. /snark.
My point is, comparing yourself is a one way ticket to instant and constant hell. No matter how you look, there will always be someone who has a nicer butt, or smaller feet, or a longer waist, or more glowing skin. Why not focus inward and love yourself exactly as you are? My guess is that the people around you think you are beautiful. If you are afraid that James will leave you if you don't look a certain way, then ask yourself two questions: 1. Is that true? and 2. If it is, is that love?
It is entirely possible to love your body exactly as it is, AND to do things to nourish and strengthen it. But do it out of love and not out of fear and loathing. If you concentrate on doing your best and loving yourself, there's nothing but happy. If you are trying to pound your body into submission and punish it for not looking a certain way, when you get to the end of a miserable process all you're going to have is a beautiful well-toned body that you will continue to compare to others, find lacking, and hate.
My advice, then, is, skip to the end: you think you need to look a certain way in order to love yourself. Try loving yourself first, and then lovingly move your body toward looking its best and being its healthiest.
And JustJess, next time I am in tears at 7:30 in the morning because I hate my eyelashes/skin/thighs/waist/whatever, please make me go read what I just wrote