The key for me was in acknowledging that I am not a machine and cannot be productive every single hour of the week. For the past 6-7 years I've been struggling with anxiety disorder and it's only recently that I discovered (with the help of a psychiatrist) that part of it was being caused by me setting unrealistic expectations on myself. Todo lists are great, but to prevent unhealthy obsession, at the end of each day I would focus on what I got accomplished rather than what I didn't get accomplished. Also make sure the list is reasonable because if it is not, it will just draw attention to how (seemingly) unproductive you were that day.