I'm going to be real here...
All the time, especially in college, I hear about people getting rejected based on the way they look, or a personality flaw.
Growing up I didn't have the self confidence to ask out a girl, because every time I did it seemed like I was rejected...hard!
But like I always say, I love rejection, because it makes me realize I need to change.
If you get rejected because of the way you look, then make that change, and make that person feel like by rejecting you they just made the biggest mistake of their life.
Sometimes people just don't see your potential (And that can be a positive for you). This can be in relationships, in careers, or quite frankly anything in life.
When people don't want to take the time to invest in you at your lowest, then you know not to give them your attention when you are at your best.
Don't get me wrong either, it's not always a physical quality people choose to reject you over, it could be a personality trait as well.
Whatever it is, you need to take that, and turn it into something positive. You can never let an external factor effect an internal result. You become who you want to become because you want it, not because someone else wants it.
When people choose not to invest in you, and then you come back and catch them by total surprise years down the road of how you great you turned out, there will be no better feeling for you.
You don't need to waste your time on people who didn't invest in your potential, because if they didn't' want you at your worst, they most defintley do not deserve you after you got better.
I don't care what your situation is, go GET BETTER for yourself, and go make other people feel like that not investing in you was the biggest mistake they have ever made in their lives.