It might also partially be that the activity and movements of writing by hand put you in the zone better than using a keyboard. When you have a pen/pencil in ha

It might also partially be that the activity and movements of writing by hand put you in the zone better than using a keyboard. When you have a pen/pencil in hand, your body may feel "it's prose/whatever writing time" rather than when you have a keyboard in hand, when the multitude of activities (browsing HN for example or texting on IRC or whatever) dilutes a similar mental association between tool and activity.