Reflection is good for the soul.
Personal reflection is even better if you act on it.
You may not be an “end of the year – take a two-day retreat in the mountains” kind of person. I’m not either. I can think through and process these questions in the time it would have taken me to drive there and back. Hey, I’m all for those who love a mountain retreat, but I’m not wired to be in that much silence for that long. I’d end up trying to make friends with a bear or something.
If quiet reflection is not motivating for you, try it verbally with your spouse or a close friend. The key is to make it enjoyable, not a chore.
Regardless of your wiring, personality, or how much time you have for this, investing quality think time to process 2018 will position you for a substantially better 2019.