It is within peoples control to a degree, but that doesn't mean that it's easy or even achievable over the long haul. It's also about much more than just willp

It is within peoples control to a degree, but that doesn't mean that it's easy or even achievable over the long haul. It's also about much more than just willpower. There are genetic factors and there may be psychological issues at play. Sugar and alcohol, two of the main culprits, are also very addictive.