Where do you write your To Do list? On paper? On a white board?

I have a weekly calendar book where I jot down my personal goals for the week to include number of workouts and special projects around the house. I also add must do and appointments. I did find most useful to add my grocery list to my favorite store app prior to going shopping versus going with a list. I make decisions in terms of price to stick to my budget and the store app takes me right to isle saving me time and money