我分开一句一句翻译给你：
On the first day of tryout for the soccer team,the coach told us to run for awarm-up.
在足球队选拔的第一天,教练让我们通过跑步来热身.
I could not run for very long.
可我不善于长跑.
As I struggled to catch up with the team,I found myself fall-ing farther and farther behind until I was the last one to finish.
当我努力地跟上队伍的步伐的时候,却发现自己越掉越后,最后得了个倒数第一.
I was so exhausted that I barely had any strength left to kick the ball!
我真是累得连踢球的力气也没有了.
After the tryout were over,my name wasn't on the list.
选拔结束后,名单上面并没有我的名字.
I felt very ashamed.
我感到非常羞愧.
But at the same time,I knew I had to do something to improve my health and fitness.
但也正在此时,我意识到我是该去做些什么来提高我的身体素质了.
I didn't want to be ashamed like that again.
（因为）我不想再像这次一样羞愧难当.