One slip is an accident; two slips is the start of a new pattern—always get back on track after a single miss.
You miss your morning workout on Monday. Instead of thinking 'I've already blown it this week,' you commit to working out Tuesday without fail. The Monday miss was an accident; Tuesday determines whether it becomes a pattern.
Missing once means you've failed and should start over, when actually the key is to get back on track immediately rather than waiting for a 'fresh start' like Monday or January 1st.
Atomic Habits
James Clear
Recording each execution of a habit to make progress visible and create immediate satisfaction (Law 4: Make It Satisfying).
Lasting behavior change comes from shifting your identity (who you are) rather than focusing on outcomes (what you achieve).
Focus on the process (systems) that leads to results rather than the results themselves (goals) for sustainable progress.