Its very easy to tell someone to 'be confident',but its not easy to be confident at all.
When I look at the mirror I see all my flaws,when I'm not looking at the mirror,I can feel them. The unperfect hair,the acne,the not flawless skin and not society wise "pretty" features. How do I become confident with all those.
When I'm seconds away from a performance,every bad thing that could ever happen rampages in my head. My heart starts to race and sometimes I get dizzy.
But even in little things confidence can be difficult.
I love making new friends,but I can never bring myself to approaching people. I can't even order something from a fast food restaurant. I get so bothered by the presence of people around me. What they think of me doesn't matter to me,nor should it,but the very presence of those people and what I think of myself mentally destroys me.
Its so easy to give people advice,but actually doing it is life changing.
Even in the little things.
You can start saying good morning to strangers,do more activities which involve other people. Start small then go big.
A small little hack to begin with : You can start by pretending to be confident,sooner or later you'll realize you are confident after all,you just never really let yourself out.
The most important thins is knowing who you are and accepting it. If you accept who you are,then you wont be bothered by other people's ideas of you. If you think your good at playing the piano,then show people,don't be afraid to express yourself. Then you'll feel how good it is to have other people share interests and thoughts with you,then you'll get used to it.
Your mind can change your body,and your body can change your mind.
Faking a smile for longer than 20 seconds can actually make you happier by tricking the brain.
By having a strong stance can make you feel powerful.
If others can do it,so can you.
Best of luck.