At first I thought you only wanted to challenge yourself, so when I read you were second place, I was about to ask you about why you had chosen failure. I think that you should make clear that you wanted to be first place and your reasons for it, instead of later. I don't think is cliché at all, I don't think there are many track and field athletes with asthma. Another thing is that you began decribing a scene, and interrupt it, and then suddenly you're back to the rope. It is not clear if it is the continuation of the starting scene. It also has few errors:
whispered one of my teammates
maybe this is correct, but I think it sounds better "one of my teammates whispered"
peeking at me with unease
same with here, "as he peeked at me..."
Slightly annoyed, I wanted to erupt at that moment
If you were only slightly annoyed, how did you want to erupt?
Ignoring my shaking legs
Shaky legs
head to the ground
Sorry, I didn't get this, but maybe it's because I'm not a native english speaker
Suddenly, there was only dead silence. I was left with a ruthless void of fifty yards, waiting.
I think you can work with this two sentences so you can say something like, there was only the void, you, and dead silence.
had a good two hours in bed
had some good two hours, or had a good pair of hours
'I would never become more than an ''okay'' athlete'
If your quoting your coaches, you have to remove the apostrophes or change the I by you.
my frantic nature of breathing
The frantic nature of my breathing
to consider for starting position
I would delete the "to consider"
The annual race hit: this time I had to triumph over asthma for good.
maybe a ; is better?
"Why are you letting this get to your head so much?" I asked the sad teenager in front of me. "Shouldn't you be moving on?''
This is probably the only cliché thing on it, but if you actually talked to your reflection, then I guess it's okay.
to whom I was an 'okay'
for whom?
, why I had been so adamant
remove the comma and is why had I been
I felt vulnerable all my childhood
I had felt
that I clung onto for so long
That I have been clunging
I take an earnest
I will take
Good luck!