I am currently reading chapter 3: Learn To Please Yourself. The author says that Nice Guys are seeking approval by (for example) being smart, being in good shape and dressing well. I think the book implies that there is a difference in impressing ourself and impressing others. Later in the chapter the book even advises that we should take care of ourselves (e.g. training (=being in good shape)).

The thing I can't really grasp is how do I dress well to impress myself (just an example). I mean, if no one care I would walk around the streets completely naked. Unfortunately, people care and judge us by what we wear, so I have to spend money on nice clothes.

I think I am missing the point.