If my math serves we have 9 weeks to go before the Monumental Marathon and Half Marathon. This is a good time to talk about some of the bad math you will want to avoid in these last 2 months.
Adding
At this point you should be in a nice training rhythm and most likely adding mileage at a gradual, but progressive rate. The time to add new training components is gone. If injury (or prevention) necessitates adding strength or flexibility that is fine. Just apply your gradual and progressive rule to those as well. This is not the time to add circuit training, boot camp, cross fit, etc into the mix. Anything you add at this point should be focused on allowing you to keep up with your normal training load and not adding to it. The additional stress that tips the scale towards too much can also be something completely unrelated to running that still requires time or energy.
Subtracting
There are many possibilities from which to choose, but perhaps the silliest thing runners do is to stop doing what is working. Maybe it is lifting twice a week or stretching regularly, and things are going great, so they stop. The thought is I don't need to do these anymore because things are going great. Reducing some cross training or supplemental training may be necessary as the mileage goes up, but keep doing it and stay in your successful training rhythm.
Doubling
Most runners have the necessary amount of obsessive compulsive tendencies to be successful. A missed workout or one cut short should bother you. If that does not phase you, you will probably not get very far in marathon training. However, doubling up on hard workouts or mileage to make up for what was missed is a sure way to miss making it to the start line. I spend a fair amount of time helping my runners rework weeks by determining what we drop and what we move or replace with something else. Take your frustration of missed training and use it to motivate you to plan better and hopefully avoid missing something later.
Balanced Equations
Remember in algebra 1 when you learned how to balance an equation? Running, and all training for that matter, has to be a balanced equation between stress and rest. As you increase weekly mileage and long run distance this balanced must be maintained. Once that is lost your progress will slow with too much rest or you will fail to improve or worse, end up injured is the stress is too great. If hard days get harder, the easy days need to become easier. It is the rest from the stress that actually brings about the adaption and overcompensation to training.
Good luck with your math over the next 9 weeks and I look forward to seeing you in November!