I am in Marathon training and have successfully run 2 Half-Marathons in the past 7 weeks at approx 2 hours and 5 minutes. Yesterday I went on my long run attempting to increase my no stopping or walking distance from 15 miles to 20. I think I might have gone out a bit fast and also ran into some severe headwinds at about mile 8. I ended up walking and running off and on and did finish the 20 but with many, many walks and stops along the way. My question is why I was unable to get back into a rhythm after being "bonked" by the severe headwinds? Even after I went far enough and left the winds behind (another 5 miles) I was never able to settle into a running without walks or stops pace again. I have been complemented for keeping a great pace and have been able to run 15 miles without walking or stopping. Was yesterday just a bad day because of the wind or was it due to going out to fast. It couldn't be due to the added mileage as my bonk came at mile 8. I should also note that I casually ran a half marathon the weekend before.