I can't say that I have ever kept together a large mileage week like what you might be trying to do because I haven't run for long enough to do that without getting injured. For example, after my last season of XC last November, I made a plan to get up to around 50-55 mpw, and got injured so I just couldn't finish the plan and had to finish my winter training with ~25 mpw near the end after recovering. I also am part of a high school team so there's more motivation related to that but how I stay motivated could still be important.
I am able to get going and stay on what I need to do as long as I'm not getting injured. The previous winter training season, I gave up on running after I hit my head and was worried about making it worse. I ended up running pretty well the following track season because of my base that I built during the previous XC season. My two-mile was awful and I can only assume that I would have improved more if I had actually ran that winter. Every time I think about giving up and not running that day or not running a workout I think about that winter I get up and go for a run no matter the conditions. Despite getting injured twice during my last winter training I did come back to improve my mile and 2-mile to 5:05/11:08 so far this season from 5:27/12:29.
Like I alluded to, I can't attest to staying on a training schedule for a super long amount of time because of my consistent injury tendency, but I have stayed on a running plan for a while I'm not and I can say that my previous times where I gave up on running while I could have, motivated me to stay on that running plan.