There it is 'easy'. To explain... well even the explanation is pretty straightforward, it seems to me that those resolutions that stick are invariably those made when it was "the right moment".
Sure a New Years resolution can work (don't let me put anyone off), but the 'stickability' comes down to factors like:-
- mental preparedness - i.e. does it simply feel like the right time for action?
- collection or body of information that will act as leverage
- belief - do you really believe in the need for the change or does the fact everyone is doing it make it 'the thing to do'? Do you have as they say in some circles 'Buy-in'
- life situation
- other external stimuli (imminent event, new job, family changes, illness, etc.)
Whenever you make a change - "Make it for yourself and make it stick. Good luck!".