When one is thinking about developing a brand identity from a marketing perspective, it is best to think broadly so that a cohesive system and set of principles are built to support the underlying cause. Dr. David Aaker (e.g., in his book "Building Strong Brands") puts forth a system that challenges practitioners to decompose the way they think about brand identity (both core and extended) along several dimensions, including "Brand as a Product", "Brand as an Organization", "Brand as a Person", and "Brand as a Symbol".
Although I leave the terms above undefined here (because they are defined more rigorously in Dr. Aaker's book), it is a useful exercise in some marketing and brand management classes to have students build a collage as if "they were a brand" by clipping pictures from magazines. The visual imagery is intended to connote some aspects of your core brand identity (some of your "essence") along multiple dimensions (e.g., quality, personality, attributes, skills).
Here's an example that I pieced together for myself (note: first draft, essentially unreviewed). What do you see? What does it tell you about how I see myself? If you know me, does it fit with what you know about me? What consistencies or inconsistencies do you see?