"the cross-country team" - extracurricular activities

My freshman year I joined the cross-country team as a way to "stay in good shape". I originally thought it would come naturally to me because running, seemed like a simple thing to do. My wake up call came during my first practice, when my 60-something year old coach beat me in a race. I was stunned. Never having finished last at anything before, quitting seemed like the only thing to do. My father insisted that I stick with it to see if things would get better. My couch must have noticed my frustration because he told me that I would "get out of it as much as I put into it". After that I began running just a little bit harder during practices and a few more times each week. Since then I have greatly improved and have qualified to run in two state meets. This experience has taught me not only how important hard work and self discipline are, but also not to give up.

There shouldn't be a comma after running in the first line
You spelled "coach" as "couch" in the 3rd line
There should be a comma after then at the end of the fourth line
Maybe in the last sentence you could change "but also not to give up" to "but also the value of perseverance" or something like that because "not to give up" sounds a bit awkward...

But otherwise I think you did pretty well!

Here is what I would do, take it with a grain of salt.

I joined the cross-country team freshman year as a way to "stay in good shape". I originally thought it would come naturally to me because running, seemed so simple . My wake up call came during my first practice, when my 60-something year old coach beat me in a race. I was stunned. Never having finished last at anything before, I decided I would quit . My father, however, insisted that I stick with it to see if things would get better. My coa ch must have noticed my frustration, because he told me that I would "get out of it as much as I put into it". After that, I began running just a little bit harder during practices and a few more times each week. Since then I have improved greatly, even qualifying for two state meets . This experience has taught me not only how important hard work and self discipline are, but also not to give up.

The last sentence is really standard, but I don't know what to replace it with--sorry.