The past is in my head

I can't help living in the past a lot of the time because the past has made me who I am at this very moment. How can I forget things or just push them aside when they once meant so much to me? They made such an impact on my life. How can I forget you all? The answer is I can't and I won't but the thing is that no matter what I do, something seems to always take me back and I'm confused as to whether that means I haven't completely moved on...or am I simply nostalgic?