I know it may elicit eye rolls, but I love using Github's built in "streak" feature for this exact thing. Best of all, it is public and motivating. I agree that it is hard to do something highly valuable on a green field project everyday, so I often work through exercises from textbooks (right now I am in the middle of SICP) to fill in days when I would otherwise just be directionless. I used to feel guilty for not "doing enough" to advance my career, and would "binge code" whenever the guilt built up too much, but now I feel so much more confident and relaxed, knowing I'm putting in a sustainable amount of high quality reading and practicing every day.