Looks like this one:
I find it very gratifying to flip through past months and see what I've done. Plus as the miles increase, the satisfaction of writing it down in my planner gets greater and gives me the confidence to keep moving forward with training for the marathon.
I also like doing this because I can easily add up the number of miles or the number of minutes cross-training, which helps me track my progress. Cross-training, by the way, is usually considered any other type of cardiovascular activity that is not running (stationary bike, elliptical and swimming are the first three that come to mind). I like to do a decent amount of cross-training when I'm training for a marathon since it saves my knees a bit of pounding and it's almost as effective as running, you just have to do the activity for a bit longer to achieve the same results (eg 45 minutes elliptical is like 30 minutes of running). The one exception to this rule I've found is in swimming, which can easily be more of a cardiovascular and strength training workout.
Writing down your workouts is a great habit to get into, even if you're not training for a running race. It can also be a very positive and helpful weight-loss tool, I think.
Do you keep track of your workouts?