There's a principle in alcoholics support groups called "fake it til you make it".

Fake is a sort of meaningless word. You are the sum of your own choices, throughout your life. There is no such thing as some sort of "true" you that is inherent and unchangeable, all of your attitudes, emotions, likes/dislikes are like clothes you wear. They can be changed with a pattern of choices that fall under your overarching will.

It's not easy, though, not by a long shot. So, one technique is to fake it til you make it. Pretend at first, fake whatever trait you are trying to establish. You'll find over time your willpower turns that into the new "true you". You can change various aspects of yourself, it's all under your power.

It's a hell of a steep hill to climb alone though, so you might want some help along the way. Addiction support groups serve this purpose for people trying to get past their addictions. You might need some pharmaceutical assistance though, if you have a chronic problem, so a doctor might be a wise move.