Uhhh..... character help?

[Kojiro Highwind]

Ok, so I've been trying to make stories lately in my head but the characters in them don't flesh out too well cuz well... they are all too happy and helpful .... I figured that it's because of my own personality ( happy and helpful :P) and it gets rare when I make a character that isn't happy and helpful that works well ( like a character i made that i played in a current Big Eyes, Small Mouth campaign im in :: anime based tabletop rpg::.)

Maybe someone can help me find a way to make better personalities for characters I make? Writing tips pretty much. ( I already know the golden rule of writing.... Write what you know.)