Nostalgia can be good. I’ve written a bit about it before. It can drag you into rabbit holes, too. This is usually one of its aspects we’re warned about.
But it can help your present life. It just matters how much time and effort you put into it. You shouldn’t live in the past. It’s gone.
But neither should you disdain the wonderful things that got you where you are, any more than forgetting the painful things that shaped you. The important thing is that you keep moving forward. We live in the present, always, but it helps to look where we’re about to step, too.