I find that 99.99% of new years resolutions are just empty and hollow promises.
I've been going to a gym for many years and like clockwork the gym will be jammed packed this month, and then starting in February the membership population starts decreasing back to normal levels by March.
Other promises besides weight loss/getting into shape seem destined to the same fate.
If something is worthy to undertake to improve one's physical, mental, or spiritual self then its not something that should wait until January 1 but start immediately.