Giving up

Went out with Hannah, who was biking, to pace me to do a 21min 5k. At 2.56 miles, I was 200ft ahead of my goal pace but so uncomfortable (combined pain from legs, lungs, heart and headache) that I turned around and walked home. After 20 minutes I went back and finished the 5K (in 20:25--but of course thats not my PR with a 20-minute break in the middle).