Interval workouts

Since I'm training for a 5K, my brother recommended interval workouts to help me go faster. They are brutal so far. It is quite the workout. This morning, for example, I did a warm-up then alternated 2 min very fast with 45 sec recovery. By the end of the 2 min I think I'm going to die, and then 45 sec later I get to do it again. It is tough, but the results are going to be good. This morning I went 3.36 miles in 35:52, which is a 10:40 mile - and that INCLUDES the slower pace. I am now hoping maybe I can do a 10:30 pace for the 5K, which would be about 33 min for the race.