Without confidence, nothing happens. So you are correct to a certain degree. Being comfortable in your skin and what you are is very attractive. But the point the OP is making is that how you show up is a key to attraction. It is easy to be confident when you have something to actually be confident about.
I know 300lb dudes who wouldn't know a dumb-bell from a church-bell, and would rather put a gun to their head than use the stairs and they do fine with women, because they are fine with who they are and do not give two fvcks about what others think... so it doesn't stop them. If they are okay with the women that they attract then it works for them. One guy is a fat @ss DJ, which is a strange profession, but he is a fun guy, and his girlfriend is a smoking hot chick that you would not believe. Why does this happen? He has the confidence to make an effort, doesn't care if she stays or goes, and she happens to be VERY attracted to DJs and the fact that he is funny as hell and doesn't care that he is a fat @ss.
Also... don't do anything you don't like because you think that effort is going to land you more chicks. If you like working out, dressing well, eating right and being fit because you know that it makes you healthy and helps you professionally then by all means do it. If you don't like any of that sh1t, then don't. You should have good habits but if you don't... well that's okay... but understand that the percentage of women that find you attractive is going to be significantly lower... and if you like fit attractive women, it is going to be really hard to attract and keep these women if you are not also fit and attractive. There are women that do not like working out, eating well, and have a few extra pounds, they will like you for who you are.
Be the best version of yourself that you can be, then have the confidence to make an effort, let women figure out if what you have is what they want. Then again you have to be okay if what a chick wants changes with her chaotic emotional state... if her attitude changes and you are out... then be a man and let her go find the next ride... you go find another one.