Aerobic Intervals: 4-5 rounds of (3-5 minutes work w/ equal rest).
Warmup as appropriate:
Run, row, bike, or swim
Conduct a moderate warm-up and then work at 70% - 80% maximal effort
for 3-5 minutes. Take rest equal to time of work.
If running 800m to 1200m will fall in the 3-5 min window.
Try to keep an even pace regardless of activity.