At some point in all of our lives, we haven't felt completely confident with ourselves. We're all guilty of comparing ourselves to other people and we've wished we could change a few aspects of our physical appearance, personality or whatever it may be. Especially in our age, it feels as if we're pressured to look, to act, and essentially to be a certain way that is accepted and embraced by society.
We've all doubted whether or not we are attractive enough, smart enough, sociable enough, cool enough, interesting enough, and so on. Because of this, it's become common for people to see materialism, pleasure and other external, superficial things as the sources of ultimate happiness. This is not to say we can't desire these things. This is to say that they won't necessarily make you happy. For instance, you may love hearing compliments (who doesn't?).
They do make us feel good about ourselves, but will they make us genuinely happy? No, they won't. In this case, being dependent upon other people's compliments to bring you happiness is a clear indicator that you aren't authentically happy with yourself. Happiness is not something that is given; it is a state that you inhabit, just like with confidence. I can't give someone her confidence. I can encourage and motivate her to be confident, but ultimately she has to be inspired and find it within herself to be confident. The same applies to happiness.
You may receive a thousand compliments a week, and you may still feel deeply unhappy with yourself. How do you attain genuine happiness then? It is by being totally true to you. This may sound really cliché because we hear it all the time, but it is absolutely, 100% true. Being and most importantly accepting yourself is what is going to create and sustain happiness in your life. Many times, we feel as if we need to change in order to appeal to others, but this is the worst thing that you could probably do.
Being someone you aren't won't last long, because you will eventually find yourself unhappy with constraining your actual self in order to be liked by others. By changing who you are for someone else, you're far more concerned with someone else's approval than your own happiness.
To add, the fact that someone wants you to be a different person for him or her should tell you that they aren't worth having as a friend or partner and quite honestly, they don't deserve to have an amazing person like you anyway! Avoid those kinds of people, and accept the fact that not everyone will accept you for who you are. You can't drastically change who you fundamentally are, but you could always improve to achieve the ideal version of yourself.
Staying true to who you are, your values, your interests and most especially, accepting every aspect of yourself will allow you to embody confidence and be happy.
Remember there's only one you, so share your uniqueness with the world.