I use the "don't break the chain" idea as well and it has helped me out tremendously. I currently have three separate calendars for April taped next to my computer so that I can see it every day/all day as a reminder. I will not have any leisure time until I mark an X for the day on all three calendars. The three calendars are for improving myself professionally/career (coding every day), physically (gym), and mentally (reading 1 hour).

I highly recommend that methodology for anyone trying to build a [productive] habit.