I've been working my whole life and always with one aim in mind.. to do what I like, what I enjoy and something that gives me energy. We have only 24 hours a day and if you are spending 1/3 on something you don't like .. or at a place they you don't feel comfortable, then you are in the wrong place. Or better yet, doing something wrong.
I don't know if there's any better teacher than life and though I've always had great opportunities and sometimes easy gigs, I've never stayed at the comfort zone. One always has to strive to better themselves, learn about others and give the possibility to make mistakes. And when challenges become too great, I rely on my friends and colleagues. Working alone is tough and if there's someone who can share their wisdom and experiences, you should always ask for help.
Writing personal mottos or mantras are kind of silly, but when it comes to work I have actually couple: always hire people that are smarter than you and life is too short for uninteresting things.