Unfortunately, a lot of times it does depend on the person. There are incentives that you can provide. Some people, employers, spouses, friends, provide incentives. Incentives help motivate people to start, but again, it really comes down to the literacy. You have to learn what you need to do. Behavioural change comes with finding out why you're in that spot in the first place. You really need to find out what happened to get you there. That's why diets usually don't work, because you're not dealing with the problem; you're just dealing with the outside part of it.
There also is a level of accountability and personalized guidance that comes from a specialist, whether it's a health coach, a doctor, or a nutritionist. It depends on the type of person you are. Some people can handle self-guidance. Some people need more personalized guidance. Some people need an accountability partner, a doctor, or a coach to help them.
Incentives have been found in the corporate world to help get people down the path. After that, they need the proper motivation and accountability to keep them going.