I must admit I’ve never really adopted one, my parents were such shining examples of enjoying nature, working hard and being kind and honest that these sentiments underpin everything rather than a motto.
But a few years ago during a dark time battling the self-doubt that we all sometimes suffer from (ie, why do I bother making all these things?!) I read this inscription while browsing in a bookstore:
If you bring forth what is within you, what you bring forth will save you. If you do not bring forth what is within you, what you do not bring forth will destroy you.
And since then whenever creative self-doubt strikes I remember these words, although I’m not sure this was quite what Thomas meant by it (googling this quote just now I find it is in fact from the Gospel of Thomas). It helps me to remember that in the end I make things because I can’t not, and doing so is in fact a process of self-discovery meaningful perhaps only to me, but that is more than enough reason to continue.