I don't really know either, but this is my opinion of it
I think he meant it to be that he hadn't yet found inner peace with himself so the Hulk could come out whenever he wanted, and in some rare cases be able to control when he does come out. I think when he says "...I'm always angry" it means several things. He's angry with himself, angry at the Hulk, angry that he IS the Hulk, angry at life, just...angry...and that anger helps to fuel the Hulks power. Maybe I'm just rambling now.