1) It's MUCH FASTER to start writing in.
By the time you swipe to find your notes App, load it up and start a new file, or open your computer to load up a writing tool on the browser (not to mention the typing of the URL and the many irritating clicks to get you started), nothing beats the 'load up' speed of simply grabbing your notebook, and opening up to the latest blank page.
As an entrepreneur - when they say you need to improve your TIME MANAGEMENT, it often means learn to optimize / reduce the duration it takes to do your activities!
High performance entrepreneurship values speed of implementation, and they recognize that the notebook is far more efficient to start writing in.
2) It DRAWS YOU IN to want to write more.
Once you start to be receiving the gratification of how you last completed your tasks, the goals you've hit, the achievements, you'll start to realise that your performance is highly depended upon the planning you've prepared beforehand in your trusted notebook. You will be drawn to leveraging it as your performance enhancing drug!
3) You GAIN THE ENVY of others in the workplace.
When you start receiving the regular compliments such as "That's a really nice notebook" from your peers or clients, you immediately gain that additional boost of pride and confidence, that will act as a nice supplement of energy and morale - which is just perfect for sustaining your performance so that you can complete those tasks of yours just that little bit sooner!