To break a habit, you have to replace it with a different habit. Willpower is one of the ways to do that, but others are more successful on more people.

The reason why so many people hire a coach for physical activities, diet or even life decisions isn't so much that these are extremely specialized domains that need high expertise; it's that having someone make the decision, i.e. not relying on willpower, is often more effective and easier. It also leads to accountability: you have to show results to someone else, not just to your brain. And for most people, that's also more effective and easier than willpower.

Telling people to get over themselves and take charge is generally a well-meaning, but often misleading call to action. And after a couple of failures, the lesson they'll learn is that they're weak and ineffective and there's nothing that can be done about it, which compounds the problem instead of solving it.