If you can do 4 of those you're doing well. The key is to expend every little bit of energy you can for those 30 seconds, super burst sprinting till absolute failure.

Sprint to your maximum potential for 30 seconds, then immediately slow down to a walk, and walk for a minute. Once that minute is up, back to the sprinting for thirty seconds. Keep rotating between 30 second sprints and 1 minute walks until you are exhausted.