The biggest reason people quit their habits is an "all-or-nothing" mindset. You eat one donut, so you decide the diet is ruined and eat the whole box.
Never Miss Twice
The Two-Day Rule is simple: Never skip a habit for two days in a row.
Life happens. You will get sick. You will be busy. It is okay to miss a day. But the next day, you must show up to maintain consistency. The goal isn't intensity; the goal is showing up to prevent the "spiral of quitting."