4 x half mile repeats

Rainy and cool at the lake this morning.  Started with a mile warm up in 10:04 and went immediately without rest into the first half mile.  Goal was to do 4:20 for each half with standing rest of a minute and a half in between.  The 4 halves were 4:12; 4:12; 4:23; and 4:20.  The mile cool down was 11:25.  Total time was 43:39.  Tough workout.