Today I went for a 4-mile run and was a full minute-per-mile slower that what I averaged when I ran to Panera on Friday. I'm never quite sure what makes the difference from day to day, but at this point I'm thinking maybe when I'm running I should wear a baseball cap with an extra long brim and dangle a mini-bagel off the end of it.
Finding that "thing" that works is slippery and elusive; a game of trial and error requiring flexibility and creativity. So, challenge yourself to find something that gets you going this week and go with it for as long as it's working for you. When it loses its allure, it's time to try something else.