8 rounds of 30 seconds on, 20 seconds off.

Use a treadmill, set at 12% grade at 0-30 sec slower pace per mile than best 5k pace. Do not reduce the speed!

I set the treadmill at a 7:41 pace. I accidentally paused the treadmill after the 7th interval, so I got about an extra 30 seconds of rest before the last one.