I like the spirit of this advice, but I disagree with it for myself. I don't find that identifying as a role helps me commit to that role. And one of the most insufferable kinds of people is the one who says "I'm an artist" or "I'm a writer" or "I'm an entrepreneur" and it feels like an affectation, because they haven't actually sold a painting, or written a book, or started a business. Or, they've done these things half-heartedly, once, a long time ago. I'm not standing athwart the dictionary and declaring who is and who isn't what, I'm saying I wouldn't do that, personally, because I'd feel like I was insulting people I admire if I adopted their titles without feeling I'd paid the dues.