Author: Greg Yau
This one is quite simple and does not require any pieces of equipment (besides running shoes and someplace to run at).
Basically, you run for a short interval, then walk for a short interval, and repeat. The time allocation combination for the two intervals depends on your level of fitness and experience.
Beginners: Run 10-30 seconds, then walk 1-2 minutes, repeat (1).
Intermediate: Run 1-5 minutes, then walk 1-2 minutes, repeat (1).
Experienced: Run 6-8 minutes, then walk 30s - 1 minute, repeat (1).
Beginners and intermediate runners should look to complete 30 minutes of the workout above for ~2 days a week, gradually increasing the pace of the running intervals. Experienced runners should do it for 45 minutes, ~3 times a week, and add another 5k run during the week.