What does this essay need?! (an experience and its impact)

This is basically a general short essay that I want to use for many colleges but if chosen a promt it may go well with:

Evaluate a significant experience, achievement, risk you have taken, or ethical dilemma you have faced and its impact on you.

Four years ago, my dad came up with the idea of biking through the five boroughs of NYC. "It'll be a different way to experience the city. C'mon it'll be fun," said my dad and, like most other times, I accepted his challenge. Little did I know that it would be one of the most physically challenging events I could have imagined. We were up and out early that spring morning. We got our rusty bikes in the car, and drove to Battery Park. Concealed alongside hundreds of Bike New York participants, we were as ready as we could be for the challenge. It was thrilling at first: riding on Sixth Avenue without a care in the world; soaring over the mammoth Queensboro Bridge. Just getting to feel the descent, and letting go of the pedal was a reward within itself; climbing the bridge in the first place was tough, at times I couldn't do anymore but instead had to walk up some of the way. But even as arduous as those 21 miles were, I didn't give in to any shortcuts and most definitely did not leave the tour when I was tempted to do so. Giving up is just not a part of who I am and now I realize that this was the first occasion in which I truly cherished it. Instead, I always seem to find a way to motivate myself and to reload my drive to achieve my goals. To finish the other half of the event: I stocked up energy by drinking as much water I could and devouring the bananas and granola bars provided at each rest stop; and kept encouraging myself that I will finish. Worrying, my dad kept reassuring me that it was okay to abandon the 42 mile ride; after all, we didn't even practice and we were not, in any way, fit for it. Nevertheless, I continued. Last test: the Verrazano Bridge, all we had to do was cross this behemoth and the finish line was right on the other side. The climb to the top seemed almost impossible, but, sweating and barely feeling my legs, I made it up. I got on the bike, feeling relieved while descending, and pondered how I had gotten to the finish line (even if we arrived two hours after the scheduled parade). I realized that it was my most valued personality trait that aided me through the tour with triumph: perseverance.

I'm trying to make it more personal but can't find a way to do so. And maybe a criticism would be that I should expand more on my preservarence, right?

but is this "essay" going someplace or should i just scrap it and start all over again?

"It was four years ago that my dad came up with the idea of biking our way through NYC."
"That" should be "when." Or, alternately, you could shorten this sentence by saying "Four years ago, my dad came up with the idea of biking through NYC."

"[...] persuaded my dad and, like most other times, I accepted his challenge."
"Persuaded my dad" is the wrong expression. The way your sentence is structured, it sounds like your dad was persuaded by the sentence in quotes, while I think you're trying to say that your dad said the sentence in quotes in order to persuade you. Simply "said my dad" is fine- sometimes the most common verbs are the best ones to use.

"We were up and out early that spring morning, we got our rusty bikes in the car, and drove to Battery Park."
It is grammatically incorrect to connect two independent clauses with a comma. Split this into two sentences: "We were up out and early that spring morning. We put our rusty bikes in the car, and drove to Battery Park."

"With the crowd of bikes and helmets, we were as ready as we could be for the challenge."
Be careful- sometimes the arrangement of a dependent clause can hide flaws in grammar, which is the case with this sentence. If you were to restate it so that the dependent clause follows the independent clause, then the sentence would be "We were as ready as we could be for the challenge with the crowd of bikes and helmets." Obviously, that doesn't make any sense, since you do not possess a crowd of bikes and helmets, so you need to rewrite this sentence.

On a side note: were you doing this as part of an organized event? If so, which event? That would be a good thing to include in the essay.

To answer your questions, I think this essay is indeed "personal" enough, and it certainly is going somewhere. Most of your errors are grammatical and therefore fairly easy to fix, so the essay is definitely a keeper. I would also emphasize more of the "struggle" that you went through, if you want to expand on the perseverance theme. Describe in greater detail how arduous the latter half of the journey was, how you felt like giving up, how exhausted you became. That way, your triumph will be all the more powerful in the end.