Anything. Everything.
Its so fulfilling.
And you get more shit done.
Write out your regular morning and night routine.
Write what you have to and want to do throughout the day.
Write out a short term goal or some habits you wish to make consistent.
Write future goals for future you to one day achieve.
Write a list of the important people in your life.
If you have a trip coming up, write a packing list.
Write a list of your favourite things.
Just write it down.
Trust me.