This is something we all need to be aware of to ensure we do not get ourselves into trouble in our quest to become healthier. Basically, one way of being is really damaging and extreme- emotionally and physically- whereas the other is useful and empowering.
Definitions give a useful insight:
So Obsession is defined as:
1. Compulsive preoccupation with a fixed idea or an unwanted feeling or emotion, often accompanied by symptoms of anxiety.
2. A compulsive, often unreasonable idea or emotion.
Whereas Discipline is defined as:
1. Training expected to produce a specific character or pattern of behaviour, especially training that produces moral or mental improvement.
2. Controlled behaviour resulting from disciplinary training; self-control.
Note the anxiety and unwanted emotions in the first, whereas the second focuses on possible moral and mental improvement. You could say that one is a voluntary and mindful act with positive aims whereas the other involves much less control and usually ends in disaster or is not sustainable.
So if you are going to embark on a health and well being plan this New Year, check and make sure that you are working towards discipline as opposed to developing a harmful obsession. This could help ensure you have a healthy AND happy 2012.