I am currently in graduate school for mechanical engineering/biology, but I have no idea what I want to do if/when I graduate. I am starting a blog to keep a record of my alternative journey of exploration which has little to do with my thesis, and will likely not be relevant for anybody. My main goal is to keep myself honest and assess what I have done.
A day in which one learns and creates something is a good day, in my opinion. I don't think it matters what you do, or if it will be valuable to anybody, but the act of discovery is imperative to having a fulfilling day. This is certainly not my original idea, as many others have put forth the concept of not being concerned with what you are doing as long as you are doing something, but I think it is a smart way to go.