You can find good books on attachment theory as it relates to romantic relationship (your romantic relationship is one of the best places to develop this aspect of yourself). Those books can give you an understanding of the framework.
To embody it and get it somatically the best way is to work with a coach or therapist and to get into more intimate relationships (romantic or creative) with someone who has a more secure attachment style.
Doing embodiment work, trauma work, practicing empathy and learning how to hold space.
Note -- you'll also have to be selling something you believe in and that is in integrity with your values -- otherwise you'll be working against yourself.
