One of my previous teams paid to have Fogg come in and train us on both his behavior model, and also on how to do feature planning.
The lesson on feature planning was revolutionary for my team. We went from shouting and arguing during planning meetings to everyone walking out happy with all the decisions that were made. He teaches a truly amazing process.
The behavior model itself is super useful for user journeys. My biggest take away is that when someone first downloads an application (or signs up on a website) they do so because they have a problem they want to solve, and at that moment there is a level of motivational energy that they are willing to spend. Be it adding pictures to a dating app or going through an onboarding process. If that first use is too complex, the user's motivation is exhausted and they'll drop out.