I have the impression that people (including myself, I'm not going to be ignorant) have the nature of locking themselves up if they have an 'off day'. It's a lacking of inspiration, stimulation and encouragement to go on sometimes.
Of course as a good PM or PL, you want to have the occurence of these periods as low as possible. As a PM or PL, people depend on your input and on your outcomes and if you slow down, probably the whole project slows down.
How do you keep yourself motivated on days that you cannot find the drive to go for it 100%? What are your tricks to keep you fresh and motivated?
For example: If I have a bad day (and it only happens once every few years) I oblige myself to go to one of my colleagues and ask for something. No mather what, even if it is how it's going with his work, I always come back a bit refreshed. Seeying other people work, often stimulates me to get back on track with my own job.