I have always kept a journal of every day I work on a particular novel. I favor 8 x 11.5 spiral notebooks. I note the date and the work I did that day on the novel. I also use this to list ideas as they come to me for the book. As I incorporate the ideas in the book, I check them off in my notes. I find this helpful because ideas come to me throughout the day for what to work on next or a new idea for plot or character and it is easy for me to walk into my writer room and make handwritten note. Others may favor using digital notebooks but the handwritten ones are easy for me.
I'm a serious writer, meaning I have a regular daily writing habit, and I'm interested in sharing my work through publication. My favorite literary form is the novel. I write to entertain myself and my readers.