The last straw

After yesterday, I was hoping that because of our race in the coming days, today would be a recovery day. On recovery days, I usually would go out on a slow easy run for roughly 20-25 minutes (around 2 miles). But instead, my coach came up with the genius idea to have us to a workout on an 85 degree day on the loop of a reservoir. As I made my way to the starting line all I could think was "How much more of this can I handle before my heart gives out?" I got roughly a quarter of the way through with the rest of the team before I drifted off and began to carry whatever pace I could maintain, being passed by rookies in the process. It was and still is humiliating and difficult for me to accept these circumstances; knowing that I will no longer be the asset to the team that I once was and worst of all I will never be a good runner again due to some unknown syndrome I seemed to be suffering from. I heaved back to the starting area after finishing to find my group already gone on their 2nd lap..."2ND??? SERIOUSLY???  I turned to my coach and saw him gim me an unsatisfied sigh and turn away. That was all I needed; Without a single exchange of words, I picked myself up and jogged (unsuccessfully) back to the school, got in my car, and drove away; with tears running down my cheeks the whole time. I thought "Even he has lost faith in me." I still play that question over and over again in my mind over what to do "If I quit, I let my whole team down. But if I stick with it, my heart will fail before the end of the season."