Great question - definitely inspires some honest reflection.
It's not the actual "fitness" of the body that I find attractive in people, so much as the mental/psychological preconditions to it.
The discipline, courage and initiative of someone training at ANY level is comparable- it's the desire to be extroardinary and exceptional that can exist in someone 5lbs into a 20lb weight loss, or someone who has been training for years.
Anyone who leads an active lifestyle (gym goer, or not) and takes care of themselves is a candidate, in my book. If I'm going to trust someone with an emotional, physical commitment - I want to know that they will extend the same standards of care and consideration to my life and body that they do, their own.
It's great to look at a fabulous body, provided that it's really a physical manifestation of the best qualities (strength, power, focus, passion) of its proprietor's mind. It really comes down to a lifelong commitment to always being better to yourself and those you love.
Got both? Damn, THAT's hot.