Welcome to your Watford Half Marathon Training Plan! This is a great event and was my first half marathon - I loved it! This is an 8 week half marathon running plan with cross training including swimming, cycling and strength & conditioning. It is ideal for preparing for a half marathon PR. It is based on 80/20 running methodology where 80 percent of your weekly training time at moderate intensity (i.e. at a pace at which you can comfortably carry on a conversation) and about 20 percent at ...