Fear is the path to the dark side…fear leads to anger, anger leads to hate, hate leads to suffering.

From "The Phantom Menace"

The famous qoute of Jedi master is often understood as the description of the 'dark path'. However, what's important is that anger and hate is not necessarily directed outside. 

For instance, when we fear changing or trying new things and it makes our life less pleasant, we may start blaming ourself, feeling anger slowly turning into self-hate (which may lead to mental health issues such as anxiety or depression).