Juneathon is, after all, (to quote Highway Kind) 'an annual festival of activity and excuses', so there aren't really any rules as such, but, it's nice to have a few guidelines.
So here they are:
Run or do some form of exercise every day.
Blog about it within 24 hours.
Join the Juneathon group at the Running Free website and log your runs/exercise.
Visit other blogs and leave comments, giving your support.
And that's about it really. Simple, huh?