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.