Cara, Laurie and Gilly waiting for the clock.
We often train rest/work intervals. We like simple intervals such as the 20 on 10 off "tabata" protocol or the 1 minute on/1 minute off and 30 seconds on/30 seconds off variety. Not to say these are the best. We simply like them because the are are relatively short intervals and are easy to remember. They also allow us to push hard during the work by provide some forced time to rest. The short recovery allows us to push that much harder in the next work cycle.
What is your favorite interval?