生命中最可怕的悲剧来自对自己的不信任和对自己能力的不信任,来自这样一个信念：我不可能成功,失败是我生命的唯一底色.
have occurred from因为.而发生,译为来自于,来源于.
或者 之所以发生是因为.
断句（空的地方稍稍停顿）：
the most horrible tragedies in life have occurred from a lack of faith in one's own self,one's own ability,from a belief that one cannt succeed,that failure is one's sole lot in life.