I'm very relieved. I felt pretty good the whole way and probably had a 4.50 min/km in me for another 10 then who knows. A co-worker of mine gave me a little gem during the week and here it is. She said that before a long run have a strong coffee. Supposedly caffeine increases the speed at which your body converts fat to usable energy. I can confirm I'm a lot skinnier now and I feel less fatigued than usual after a long run. I’ve fallen back in love with the running.