Watched Kstar's presentation on sitting and mobility at Google a few days ago and was struck by
the flossing analogy.
People know they should floss. They know that if they don't, their teeth may fall out and they may get gingivitis and systemic inflammation and it could kill them. But they didn't floss yesterday and they haven't died today and their teeth didn't fall out today, so they're not going to floss tonight, either. They don't feel the tangible benefit from flossing.
(As an aside, I do floss frequently but it's mostly because it feels good. And I remember my friend G saying something to the effect that he loves flossing because "it's like, man, THAT was in my mouth?!")
Fear-mongering doesn't work. It doesn't promote widespread adherence.
People need to see that doing X makes a tangible, immediate, noticeable difference in their lives.
This is why it's so important to get ppl to realize that it takes very little effort and very little time to get to that advanced novice phase, where you're healthier and stronger and fitter than 80-90% of the population. In some people it may take as long as 6 months but in other cases it can be 3-4 months with as little as 2 hrs per week invested.
It's easier to encourage adherence by convincing ppl that they won't have to worry about their IBS acting up while on a date next week, than to convince them that avoiding linoleic acid and gluten will prolong their life and lower their risk of cancer.
It's easier to encourage adherence by pointing out benefits such as clearer skin, reduced/eliminated joint pain, than "this will align your joints" or "this will reduce systemic inflammation." Make it tangible, real, immediate.