They fail due to lack of several factors;
1.Not having a plan and systems in place.
2.Misunderstanding what is the purpose behind the change.
3. Having to use willpower to action the change.
Planning and feedback are vital to success when making a change, willpower is not. When someome is accessing willpower they are relying on the conscious part of their mind, this is not where the habits and behaviours that may need changing are stored so willpower alone is just not enough.
Being able to tap into the other unconscious part of yourself, the part that runs your beliefs, goals, fears, habits, memories, dreams and learnings means you can make changes quickly and they stick, for a long, long time.
A lot of people decide, 'Right I am going to make a change' and rely on their will to power this through and yet if your whole being is not aligned with what you are aiming for then it simply will not be accomplished. It is a great idea to really look at what is it you are wanting, not the end goal but the emotion behind that, how will it make you feel when you have that thing, whatever that is. We are always chasing an emotion, it just hides behind the things we desire, the iPad, the relationship, the house, car whatever that may be, but really it is just an emotion. So sound a moment and ask yourself what I am really wanting? And then just wait, let e feeling ripple up and acknowledge what that is, what emotions are there? This is what you are really after. Then take a moment and ask your self how can I still get this feeling in other ways without needing that 'thing.' See what happens, wait and notice what comes up.
The main thing to allow yourself to enjoy this time of year is the loved ones, the times together, friends, walks in nature and a chance to say things to people perhaps you have not had the chance to say yet. Then let yourself off the new years things, really it is just a conformist way of trying to get things and never really expecting too.
Give it time and then when you are clear on what it is you really want, then make the time, take the energy to do just that, it may be on the 1st of January and then again it may not.
