In a sense it is one of the best and one of the worst advice one can hear. It also can be both. This simple notion is the most complex clichés of all times.
I get it, people not always are proficient in communicating what they intuitively think, or feel. Parts of brain responsible for that kind of understanding evolved much earlier than those which govern speech. They have good intent. But also it is easy for me to emphatically feel the frustration of the side hearing “just be yourself” as remedy for their tangible problems. Especially with social interactions.
What does it even mean?
If I am insecure and uncomfortable in social situations, what I would hear behind “just be yourself” is: "Be more insecure, communicate more awkwardly, hunch more, avoid eye contact". People who give this kind of advice miss the whole context of temperament, past experience and comfort zones of person who receives this sound-bite.
On the other hand. Related “brilliant” quotes are as helpful: just be more confident, fight it, get over it etc. Good rule of thumb for every friend and parent with good intention over there: If your advice can start/starts with the word “just” it’s probably not very helpful.
Being yourself, expressing yourself authentically is actually very hard
Imagine that in next social situation you would not be constraint with stress levels higher than what motivates you to get result in Tetris. Imagine that you would not feel the need of validation. Imagine that you would not feel the need of any auto-censorship by any social convention other than golden rule (treat others as you want to be treated). I think this is when you could authentically express yourself. And this is really, really hard.
Why? Because we’re not always aware of hormone levels that affect our behavior, of what intuition decided for us per that situation.
How to be more of yourself?
1. Figure out your strengths and weaknesses
2. Avoid putting yourself in strict shelves of temperament/personality types. You’re much more complex even than best of them
3. Try and find what really fires you up
4. Think about your principles
5. Think about what you would do without constraints of your hormone levels and beliefs about social interactions. It’s hard to imagine, but start with something. Start with "what if you would stay calm and composed?"
6. Learn more about social skills – observe yourself and others. How people communicate and what mistakes they make?
7. Exercise your social muscle as you would exercise abs. Unused muscles disappear
The whole idea, as you can see, is to know yourself better. In systematic way. As you would characterize a character for a novel. That will widen your empathy towards others. Wrap your head around social skills, tips, tricks, methods etc.. This will give you understanding, that we all ride the same cart. And the most important part – exercise that social muscle.