I need ideas for my personal project

I honestly don't know what to do. Some of my friends said it doesn't really matter what I do for my personal project as long as it's something I'm interested in but then some other people said that it's a great opportunity to start a project that can be long-term or influencial that's related to the subject I want to major in (bio or chem, something med related).
Even if I do choose to do a project that I'm personally interested in, I honestly don't know what I can do.