What's so funny about this story is that you sound exactly like me when I was just about to graduate high school and start college. Ahhh... the memories.
I used to be just like you and had this mad crush on this girl. I felt like this girl was the hottest thing in the world (I would want to bone her over a hot celebrity). Tried everything in my power to get her to go out with me in high school and failed every time. Finally, I figured I would go to college, study hard, work out, and essentially become a new and improved me. Once I was able to achieve the 2.0 version of myself, I would cooly reintroduce myself into the girl's life where she would instantly fall in love with me.. and my coolness.
But I learned that nothing goes according to plan... and that was a good thing.
Once I entered college, I commenced operation self improvement. I went to the gym 5-6 times a week, studied hard, and most importantly socialized (went to 2-3 parties a week and made a bunch of friends). This went on for my first year of college, during which I didn't speak or talk to the girl I had liked in high school.
When we finally had a mini high school reunion, I saw the girl I had been after in my younger days. By that time, I was in the best shape of my life, I had decent grades, and had been on numerous dates. But the girl? Freshman 15 had hit her hard, she had terrible grades, and even a worse social life. Suddenly she didn't look too attractive....
Fast forward a bit.. At the end of my sophomore year of college, she invited me to a party (since I was in town visiting my best friend). We all got drunk and she admitted that she found me attractive. She even tried to make out with me and take me upstairs, but I declined cause I had a girlfriend at the time.
So whats the point of this whole story? See... while I strived to improve myself and succeeded... I realized that my success wasn't due to the fact that I looked better or was smarter than I previously was. It was the fact that once I entered college... without even noticing... the girl that I had liked before wasn't important to me anymore. I mean... I think I was blind when I was in high school cause all I saw was this one girl who was extremely hot to me, without even trying to open my eyes and see that there are girls out there that are even HOTTER. Obviously that changed when I started going out with HB8's and 9's all day.
Now I'm not telling you that improving yourself both physically and mentally won't get you the girl.... What I'm trying to say instead is that the BIGGEST improvement anyone can make is in their attitude.
With that said... DON'T consciously alter yourself for this girl but do it because you want to, for YOURSELF. The day that you realize you don't give a **** about this chick, is the day she'll want to bone you. That's just how it works.