Steve J mentioned the McMillan pace calculator, so I plugged my recent 10K time into that. Here's what it came up with. And I don't even have to write it all out!
Those sound a lot better! 9:33 to 9:55 miles for my "speedwork" give me a lot more latitude, and I might even be able do a repeat. One, maybe.
Those sub-5:00 marathon predictions really kill me, though. My PR from 9 marathons is a LONG LONG way from that (5:52). I'm pretty far from running that 2:21 half marathon, too (PR 2:36). My running endurance sucks! Oh well, the only thing to be done about it is practice, practice, practice until I get it right!
I'll stick with these targets for my runs for a while. That means long runs all have to be 12:52 min/mile or faster, do you hear me!? And tempo runs below 11:05 min/mile, because that's what I'm capable of. Even though it feels much more comfy and familiar to be plodding along much much more slowly.