My ex and I are starting to talk again. She seems like she is starting to warm up to me. But she keeps saying that even if we got back together it would be the same and that she wouldn't be happy. And we wouldn't be happy. But I need to show her, that I can make her happy, because I have changed so much. Does anyone have any ideas as to how to make her realize what she is missing and that I have changed and she can be happy when she is with me?
Thanks

Because she talks to you you think you have a chance at getting her back?? She has already told you how she feels so accept it. Leave her alone. Change for yourself and if she cares to look she will see it. She knows as well as we do nobody makes permanent changes that fast.