Well, I believe you don't need a new year just to change your ways. You can always do it anytime. Maybe people are just inspired to change because of the feeling of something new for the new year or growth.
Self-control will always be the same process, but the time you implement it will be different. Practice it often until it becomes a habit.
That's what I also think, people always attribute the beginning or the year as a time to set resolutions yes I think setting a resolutions is helpful but it must not be a new years thing many who do so and if they break their new years resolution they most of the time leave it again to another new year but you can always set good habits at any time even if broken you can still get back up. So always remember you can have self discipline in gambling at any time.