I've definitely noticed basic stuff like sleep, diet, and exercise help to keep me focused. Exposure to sunlight helps, too. But there are still many days where I don't get much done even when I've got everything else right.

I have a similar situation to yourself. Honestly I have found that working environments become "soiled" for me over time. I try to constantly mix up where I am working in my place or get out of the house to a coffee shop to work if I am not focusing. Keeping s good rotation of these work spaces has been a huge boon. Often times I work from the couch in the living room, take a break, move to the kitchen, then end the work day in bed without the TV on. Eventually I will probably move back to working in my office but since the new WoW expansion has come out my office is no good for productivity.

Thanks, this is good advice. I'll try it.