This is the most comprehensive summary of the topic. It has been a nightmare for many and it got so much uglier with the emergence of smartphones. If, as you explain, my motivation is value of the task times how easy it is to complete smartphones always win. Because even though my dissertation project is very important I have my doubts regarding its completion. And phone? It's in my pocket so it's super easy to use it. Oh no! It's in my hand already :)