My self-esteem and entire self-image goes up and down all the time.

I´ve noticed that I often feel better about myself, when I´m not depressed
and naturally worse when depressed.

However, I´ve also noticed how viewing myself in a positive way and thinking I´m capable and full of potential lifts my mood immensely.

So how do you think it´s connected?
Do I feel bad and then feel bad about myself or do I feel bad about me and that´s why I´m depressed
and how can self.esteem uplift depression or is the only way to be less depressed for more self.esteem... confused!