I would change my work ethic. I am the absolute worst when it comes to assignments; I procrastinate hardcore. I am not motivated to do work unless there is time pressure to urge me along, when I’m forced to focus and get it done. Otherwise, I just won’t. I get the job done and get it done well, but getting to that point is extremely unpleasant and stressful.
I would make myself less dependent on others’ approval. Even if I dislike a person, I want them to like me. I wish my confidence was not rooted in other people’s opinions of me, physically and otherwise.
I’d want to be less self-conscious and be able to talk to people more readily, rather than being reclusive until they make the effort to approach me, or we’re in a situation where interaction is inevitable.
There are more things about myself that people would generally think of as “negative qualities,” but I’ve embraced them as part of who I am. I don’t necessarily see myself as any better or worse off for them.