Very nice, too. I cut it a bit short because Brent was finishing up; also I do not want to overdo it. But the short bursts of harder-effort running are very enjoyable, despite heat build-up issues!
I was working off Lauren's description of a stride workout she did a few weeks ago - she had 20 x 25 seconds at 1-mile race effort with one minute recovery.
I wasn't at all sure what would count as 1-mile race effort, and figured I'd better start conservatively. I took a set rest after the first 10, then did six more at a faster pace - I think the faster one is the appropriate one, the first ones were definitely too easy.
10 minutes warmup
10 x 30 seconds @ 7.5mph (8:00 pace), 1:00 @ 5.5mph (10:54 pace)
5 minutes walk
6 x 30 seconds @ 8mph (7:30 pace)
I'll try and do a straight 20 x 30 seconds @ 8mph one day next week - I think it should be doable, and it is a highly mentally tolerable treadmill workout!