Thanks again, everyone, for the inputs. I appreciate it.
Again, replying here in this post to multiple posts above.
Yes, I do totally understand that at my current fitness, I am nowhere close. But I hope that in 25 weeks I will be. I'm gonna try. If I fail, that's okay.
I picked the sub-3 goal because if I didn't, then I probably wouldn't commit to it and will fall back to running inconsistently as usual. I just want it to be difficult enough (50/50 as one of the posters put it) but not impossible. I feel like I do best when there's pressure on me.
I'm not getting younger. I consider this my best chance to do a sub-3. If I find out it's not meant to be, that's okay. At least I will have tried.
Thanks for the point about doing a long 3hr run. I can probably do it on the weekend when I don't have to work. Will try and build up to it slowly. And also for the threshold 800/1000s workout. I've never done that before. Will also look into cross-training more.
Dusted out my copies of the Pfitzinger book, the Daniels book, and a couple other injury/strength books.