done it. I’ve invented a two-step, sure-fire diet plan, the secret to successful weight loss. Here it is:

  1. Pick any existing diet that is low on calories.
  2. Write a mega-bestselling book about it with your picture on the cover.

The hardest part of any diet is sticking to it. But if you’re the originator of your diet, the incentives to stick to it, and the disincentives against dropping make perseverance a snap.

From your diet you get much more than weight loss. You get your whole sense of self worth. Your identity rides on the diet’s success or failure.  And should you ever stop practicing the diet you preach, your fat deposits will expose you a hypocrite. Either that or a charlatan whose diet doesn’t really work.

My diet scheme is so brilliant, you’re probably wondering if it could be applied to other campaigns of self-discipline.  And it can be. Personal trainers have a huge incentive to stay fit. Dress-for-success coaches have a huge incentive to dress well.

But then there are people like me, us psychology bloggers, authors, therapists and coaches who also apply the equivalent of my diet scheme. We cultivate a public brand association that links our identities with a psychological diet, some form of moral self-discipline that we counsel people to live by.

As a profession, psychology has been around only a little more than 100 years, but in other forms it goes all the way back.  The clergy, the astrologers, the sooth-sayers—all public moralizers. I think of what I do in these pages as very much like writing a Sunday sermon.

Many of us enter these professions for personal reasons. Like the diet book author, we aspire to cultivate some transformation in ourselves. As people, we’re notoriously quirky. Whether the profession makes us quirky or we enter the profession to deal with our quirkiness is an open question.

Sermonizing has earned us, at best, a mixed reputation. The clergy are notorious for hypocrisy, a reputation that carries forward, often deservedly to us.

We preach a good game. We talk the walk so convincingly. We have to-it’s the only way we can become convincing authorities to our readers and clients. But soon our authoritative style convinces ourselves. We simply assume we’re walking our talk too. We decide we’re the already-healed healers serving the people who need healing.

Why does my diet book scheme work so well for diet-book authors, personal trainers and dress-for-success coaches, but not as well for us sermonizers?

The answer is simple. It comes down to one of my favorite nine-syllable words: “Operationalizable,” which means to come up with a clear objective test for whether something has happened or not.  The test doesn’t have to be a perfect test, indeed it can’t be, but at least people agree on it.

Diet, fitness, and dressing for success are highly operationalizable. Setting aside radical changes in metabolism, we can all spot a diet-promoter’s hypocrisy at forty paces. If a diet-promoter is gaining weight; if a fitness coach is getting flabby, if the dress-for-success coach is frumpily clad, we see the hypocrisy right away. If they never walked out into the light of day, we wouldn’t be able to tell whether they were walking their talk. But then they couldn’t really pedal their wares.

Operationalizing psychological and moral self-discipline is much harder. Hypocrisy practiced behind closed doors, the preacher’s misdeeds in his sanctuary, the therapist’s misdeeds in the privacy of his own home-we can talk the walk without having to always walk the talk always.

With these non-operationalizable forms of self-discipline, my diet-scheme can backfire badly. Our talk becomes a substitute for our walk, not a complement to it, we can talk it instead of walking it, rather than walking it because we talk it.

To name it is to begin to tame it. Beware the therapist who comes on as too much of a already-arrived authority. Beware the blogger who preaches morality as though they’ve proven that it’s easy to choose and walk the moral path.