You can skip a run now and then, or juggle the plan some depending upon your schedule, but do not cheat on the long runs

Speed
A general recommendation is to do your long runs at one to two minutes slower than you plan to run the marathon. If you don’t know what this pace will be, just do your long runs at a pace that allows you to hold a conversation while you run.

The important thing is to cover the distance, not to see how fast you can go.

Walking Breaks
Walking breaks are a great way to make sure you finish your first marathon. One popular strategy is to walk through each aid station along the marathon course.

Walking breaks during your long runs can also be beneficial. Waling breaks will let you practice for your marathon experience and they will better allow you to finish, and enjoy, your long runs. I suggest 20 minutes of running, to a two minute walking break.

Cross Training
One day each week is set aside for cross training. Cross training is any form of exercise that allows you to used at least slightly different muscles than used during running. Some examples are walking, swimming, cycling, and weight training.

Rest
Rest is a very important component of your marathon training plan. Make sure you get the sleep you need and that you take complete rest days on the days designated for rest in the plan.