1. Avoid using passive voice
Ex. Instead of writing "The sound of his voice will never be forgotten", try "I will never forget the sound of his voice".
2. Get crafty in cutting down words & only tell the stories that need to be told
It's a pain, but there's a character count to comply with. Hone in on the essential details: does the reader need to know it was a Friday evening in October? Or that your student athlete's family live in a Southern California home? Can you convey Greg's influence in fewer details? While the anecdote about the oranges is sweet, for the sake of brevity it would be best to leave it out.
3. Focus your personal statement on... you!
You've given us three engaging stories, but in the end it's a little difficult to discover who you are in all of this.
It seems like you learned a lot from your experiences & from Greg - if you could give an example of how you applied that knowledge in practice it would improve your statement immensely. If you can, use that example to show (not tell) your positive characteristics.
4. Cleaner transitions
The transition between your first and second paragraph could be cleaner, it wasn't immediately clear to me what your new role was. Try, "Half a decade later, as an athletic trainer..."
Also, rework this sentence, it makes it sound as if you are already a PA: That singular event became the starting point of my physician assistant journey, motivating me to expand my clinical knowledge and skills to practice medicine at the highest level as a physician assistant.
Overall you're off to a good start! You just need to cut down on the wordiness & make sure you focus the spotlight on yourself and convey why *you* want to become a PA. Good luck to you!