6 miles, intervals, indoor track

I've sworn off interval speed training for about a year. I tried it for a while but it seemed that my body couldn't handle running sub 7:00 pace with any consitancy. I think I'm stronger now, so I decided to give it another shot.

1 mile warm up - 8:10
200 meters walking
1 mile - 5:59
400 meters walking
1 mile - 6:29
400 meters walking
800M - 3:27
2oo meters walking
800M - 3:40
200 meters walking
400M - 1:34
200 meters walking
400M - 1:34
200 meters walking
400M - 1:41
200 meters walking
400M - 1:38
200 meters walking
1 mile cool down: 10:00

I was gassed after the second mile repeat so the 800's and 400's were pretty slow but still really hard.