You got out there and did it - counts for a lot putting yourself intentionally into the pain cave. Nice time, too.
putting yourself intentionally into the pain cave
I've always assumed that was part of any serious (or even semi-serious) training program. Right?
Where's your HRM? Doggin' it for sure...:-).
Haven't been wearing a HRM since the last one died a couple of years ago. My guess would be that the number would have been in the high 150s for the first mile, 160 or slightly over for the second mile, 162-164 for the third, and maybe 166-168 at the end. That's based on how it felt, what my heart rate would have been at a similar effort a couple of years ago, and a guess as to how much my max has slowed since then, when it was just over 170. Bogus? Who knows. :-)
The pacing was excellent, just what you want. A little left to do the last lap faster, but not much.
Of course that's part of a plan, but it's very easy to talk yourself out of it, especially when the experience will be solo.