For anyone starting, my whole system is one index card and a cheap kitchen timer. The card has three rows: morning routine, protein at lunch, ten-minute walk after dinner. I tick boxes with a pencil and allow two misses per row before I simplify the card.
Four attempts got it down to six lines, because anything longer I ignore. The timer handles the walk so I don’t negotiate with myself. Weekly review takes five minutes: keep what got ticked, delete what didn’t.
It is boring, which is the point. What’s the smallest tracking setup that survived your first month?