This might be obvious, but your mind can be altered by remembering the past. Not physically, but its state.
Say you want to be productive now, then start by trying to remember a time when you had a very productive experience. Virtually go back there and remember how it felt, then take a look around and analyze the surroundings. Then come back and take this feeling with you. If you miss something in your environment, try to fill it in.
Do you feel better? Did it work?