I just wanted to thank everyone for their feedback and give a quick update.

I did the same-ish tempo interval workout last night. This time, I slowed the interval pace and decreased the recovery time from 0.5 miles to 3 minutes (12 mm). I decided to slow the pace because my legs were tired going into the run and because of the shorter recovery time. The effort level felt about the same and the recoveries seemed to be sufficient. The intervals still felt progressively harder, but a lot of it was mental. I also felt like I *could* have done a fourth interval, but really didn't want to.

My plan is to stick with this workout until it either gets easy or my focus is no longer base building (thinking late spring). After that, I plan to rotate between short intervals, long intervals, and regular tempo runs.

Thanks again everyone!