I set up a page in my journal with six of the daily features I've been tracking consistently for the last n months. I added 20 checkboxes for each of these features, and colored it nicely. I then started tracking these features with giant Xs as the days went by. One of them, walking 10k steps in a day, I didn't do. I still want to track it, though. What I wanted most for this "I missed" tracking was a grey marker. I looked through my pens, they are all colorful. I looked through my extras pouch of markers, they are all colorful. I was bummed I didn't have a grey marker, but not overly motivated to purchase one by actively going to a store for a grey pen.
To my delight, I found a silver pen in my pens cup. Close enough.