Understanding "Self" is the foundation of all development. To know thyself is often a lifetime in coming and yet how can you imagine progressing very far in any direction without it. Are you a student? then what should you study? What will naturally excel in and what will you struggle with? Are you embarking on a voyage of personal development? Then surely undertaning what makes you tick is fundamental to its success.
Even your health management is determined by your personality. You may struggle to go to the gym because it is entirely the wrong type of environment for your personality and yet with an understanding of "self" you would know this and not beat yourself up for failing to go to the gym. You would also know what kind of environment you would enjoy exercising in. For many years I struggled with team sports. The coaches hated having me on the team as I was more trouble than I was worth. They often told me that I wasn't a team player. And you know what, now I know that they are right and that's OK. I am not a team player in the sense that I am better at solo sports. This is not a failing on my part, it is simply a function of my personality. I wish I had realised this twenty years ago as my life and everyone else's would have been easier.
There are people at your work that will drive you nuts. You may take this personally but in many cases it is simply a function of personality mismatch. There are personality types that you are naturally poorly disposed to. It's not your fault and it's not there fault. Knowing this can make work much more bearable and somehow you find some behaviour more forgivable.