Nir Eyal states the central claim that lasting behavior change requires an accompanying identity change and recommends making an "identity pact." He argues, using examples from religion (a devout Muslim) and lifestyle (a vegetarian), that attaching a noun/identity to oneself makes desired behaviors automatic.
Chapters
I'm a morning person. I'm a Sagittarius, I'm well, whatever, right? You hear people having all these identities that just don't serve them. Instead, we can create identities that do serve us. So one of my favorite mantras that I made up from this book and repeat to myself is that behavior change requires identity change. Behavior change requires identity change. So I talk about in the book this idea of making an identity pact. This comes from the psychology of religion that we know that when people attach an identity, a moniker, a noun to themselves, they become much more likely to follow through. So when someone calls themselves a devout Muslim, they don't say, I wonder if I should have a gin and tonic. No, a devout Muslim doesn't drink. It is who they are. A vegetarian doesn't wake up in the morning and say, oh, I wonder if I should have a bacon sandwich for breakfast. No, vegetarians don't eat meat. This is who they are.