The comedian Mark Normand has a bit where he goes:

"Girls say 'Mark, you just need to be yourself.' Or 'Mark, you need to act confident.' Well pick one, I can't be both!"

"Just be yourself" is effective advice when it is interpreted as not putting on an act or pretending to be someone else because you don’t think that you are good enough as you are.

People highly value authenticity. When you put on a front, it signals to others that you are trying to cover something up. By actively and try-hardily attempting to create a positive image of yourself in other people's minds, you most likely only end up making yourself look worse.

However, if you are a super unconfident, needy, validation seeking person, then communicating these unattractive traits, even if done so in an authentic way, is also not going to benefit you. Thus you should work to become the best version of yourself. This is done by improving yourself and your social skills so that you can honestly communicate what makes you attractive.

Link to Full Video: https://youtu.be/cpKbR8Cz3Tc