On days I want to get work done, I change my environment ever so slightly to change the tone. My PC I work at is the same as the one I use for entertainment, so this part is pretty important for me. Maybe you put up a shoji screen or change the temperature of the lights in the room, or open the blinds. Maybe just throwing on some background music.. Whatever ends up working for you.

If you have the freedom to do so, dedicate a weekday as a day to get non-work stuff done. I call these my admin days.. Days that are dedicated to doing chores, shopping, making appointments.. That sort of thing.