A paper notebook is not a substitute for every digital tool. It is simply a useful space where an idea can stay unfinished. There are no notifications beside a sentence and no requirement to organise a thought before writing it down.
Give the page a small job
Write three things you noticed, draw a rough plan or collect the questions you want to return to. A page does not have to be productive to be worth keeping.
Let the habit stay flexible
Some weeks you will fill many pages. Other weeks a few lines will be enough. The notebook is there to support attention, not to become another task to complete.