I remember my very first sketchbook. It was given to me by my dad after I showed interest in owning one. I bet he wasn't sure at that time what I'd do with it. If I would even use it for drawings, or I'd just cut the pages out and use them as "fabric" for my paperdolls' dresses. I may have eventually used some of the pages for that purpose, but I did use it mostly for sketching. It became one of my favourite hobbies.
I wasn't good at it. It's still not one of my strong suits, but in a way, I developed my style. I can't do portraits still, which is my frustration. But I like that I'm able to draw my ideas, at least, or just be able to doodle when I need to clear my mind.
Keeping a sketchbook or a visual diary has always helped me in my design process. Also, it's nice to be able to look back, especially when you're fresh out of ideas, or in need of an inspiration.