In her book, she writes about how many of us have developed what she calls a list of "worthiness prerequisites." As in, "I'll do x thing once I'm (thin, rich, educated, trained, etc.) enough."
In other words, there's a tendency to shame ourselves out of pursuing what's most important because we feel some kind of embarrassing lack. For example, I have a weird hang up about teaching yoga because I can't do a handstand away from the wall. The fact that I've never read either Joyce's Ulysses or Pynchon's Gravity's Rainbow is a source of shame for me as an English professor.
This sense of shame or not being whatever "enough" can prevent us from doing the very work that makes us feel most accomplished--whether that's throwing our voices out and teaching yoga publicly, or putting pen to page.
The fear of being unworthy of writing ideas afflicts graduate students especially. In my old job as a writing center administrator, I often worked with Ph.D. students who told me that they would write when they had read "enough." The truth is, those students were the ones who tended not to finish.
Ironically, enough is never enough.
To combat these feelings, Brown suggests cultivating a feeling of being "Worthy now."
I'd put this a little differently: write now. yoga now.
Writing now makes you a writer. Teaching now makes you a teacher. Practicing yoga makes you a yogi. Doing the very things that are scary actually has the effect of fighting the shame-anxiety that surrounds them.
Shame is about externality--past judgements and fear of future censure. Daily practice is about doing things in the present time. Rather than being momentus and thus potentially shame-inducing, daily practice normalizes the process, making it a day to day routine.