In a previous post, I discussed how I enjoy doing new year's reflections with my kids. I think this is an excellent went to get your children to being to have a sense of mindfulness and appreciation.
There's lots of opportunities for reflecting on the past year and setting new goals - it doesn't have to be on January 1. The end of the school year is a great time for school aged kids to do this type of reflection.
Here's an example of a year in review template (fun for grown-ups, too!)