Good news! The workout that I'll plan out but never do has just gotten shorter. In high-school we had a similar workout we called "intervals". We would run them for anywhere between 100m and a mile. A 30 second one would be usually less than 200m (based on the ability of the sprinter of course), and weren't too bad, but the mile ones (about 6min for a slow-poke like me) were gut wrenching by the time you were on the last few.