Research Shows:

Journaling and gratitude practices are documented to reduce an array of stress by clearing mental overload and shifting attention away from worry.

• Writing stops thoughts from looping.
• Gratitude trains your mind to notice what’s working instead of what’s wrong.
• Together, these habits improve mental health and overall
  well-being in ways that have been measured in controlled scientific studies.

Furthermore,

Writing Goals and Planning Your Day Creates Real Success.

Thinking about goals doesn’t change your life. Writing them down and planning when you’ll act does.

In one study summarised by Michigan State University Extension, 76% of people who wrote down their goals, wrote action steps, and reported progress achieved their goals

• Writing creates clarity.
• Planning creates commitment.
• Together, they turn intention into action.
  

In practical terms:

Your chance for success is more than three-quarters guaranteed when your goals are written down and planned into your day.

Planning makes action easier because you've already decided what to do and when to do it.