I'm in the midst of a weekend away to complete my plan for 2018. I did the same thing last year and it was a great habit to begin.
This may be obvious: when you have a plan with a vision, goals and a mission, it's certainly easier to achieve important things.
For decades I didn't actually plan much professionally or personally. I just did.
I wish I'd started formally planning sooner.
I've really fallen in love with a couple of planning tools given to me by my excellent business coach, Tom Cuthbert.
I love the simplicity of these tools. However, completing them is hard. They require lots of thought to do well.
You can find the two worksheets here from Tom's page of resources:
1) Reflections - Step back and think about the past year. What went right? What went wrong? What did you learn?
2) Goals - Write down goals for the year, why you're on the earth and what are your super-powers. I love that both professional and personal goals are listed.
Once a quarter, I look at these documents. They are great to reset me back to what is important. They make sure I'm working on the correct stuff.
Lastly, these are living documents. So, I'm not afraid to acknowledge situations change and modify goals for the year. Good luck!