It's a great question, isn't it?
Too many of us are not very kind to ourselves. How often have you said to yourself "you look fat", "you could have done better", "what is wrong with you?"
If that voice was a real person - would you be friends?
I doubt it. You'd get away from that person - as fast as your little legs could take you, wouldn't you?!
A real friend gives you a pep talk when you need it. They give you empathy and sympathy when things go wrong or when you're sad. They listen, and let you speak until you have no words left. And sometimes they drop round with flowers or chocolates. Just because. Just because they're nice.
And sometimes they have to tell you stuff you don't really want to hear - the cold, hard truth. But it's only when you refuse to see what should really be so clear to you. And once they tell you, you know they're right. A good friend knows that sometimes hearing the truth hurts, but they always deliver it in a respectable way - in a way someone who cares about you delivers a hard message because it's going to help you make a better decision or the right course of action.
So.... start turning your inner voice into your best friend.
Be honest with yourself when you need to be - but mostly, be kind.
Be nice. Be respectful of yourself and your feelings and most of all?
Give yourself a break, stop beating yourself up about all the things you're not and start to congratulate yourself and compliment yourself when you do something good.
Be the friend to yourself that up to now, you only used to be for others.
Be your own best friend - it's a relationship you'll treasure forever.