Running in late 20s

I first came across UTMB in July 2013 when I ran my first ultramarathon. When I registered for the Swissalpine K78, I noticed that the finishers will get 2 UTMB points. After I finished that race, I came back and read about the UTMB, a 168 km race with more than 9000 meters of elevation gain. At that time I had no idea about this distance, but I set myself a long-term goal: to qualify and run the UTMB. Then I ran the Eiger E101 and the Swiss Irontrail T81 in 2014 to collect the remaining points and registered for the UTMB.  UTMB profile We arrived in Chamonix on Wednesday. This time I had my sister as my supporter. Shortly after our arrival we went to the expo (Salon Ultra-Trail) I needed to buy a new backpack as my old one was torn off. And just after 4pm we went to collect my bib number.  it was a long queue and it took more than eighty minutes to get to registration point. First of all there was mandatory gear check. They will provide you with a tray that you should put th

It is 47 km into the race and I'm  walking downhill through a forest towards Burglauenen. It's been a great race so far.  I passed the last check point (Faulhorn, the highest point of the race) 15 minutes before my expected time and enjoyed running downhill to Schynige platte.  A few minutes ago, when I approached a corner on this muddy terrain,  a sharp pain hit my left knee so badly that forced me to stop. I cannot run anymore, I am using my walking sticks to take some weigth off my knee and slowly walking down. I could have run this part of the race quite fast and effortless if my knee didn't hurt. Through my training, I put so much effort to master my downhill running technique and I was quite confident in it that I'd consider it as one of my strength points. It hurts a lot when you have trained a lot and on race day you just cannot perform well. In fact that is hurting much more than my sore knee. As I am limping cautiously, there are many runners passing by, mos