The art of lasting change is not about willpower or one heroic effort. It all starts with habits.
"A habit is a behavior that has been repeated enough times to become automatic." (James Clear, Atomic Habits)
Habits only become habits when there is a shift in lifestyle that allows for that activity to exist. Every time you practice a habit, consider yourself taking one step closer toward a larger outcome, whether it's desirable or not.
Eating sweets before bed every night will lead to unwanted weight gain over time. Eating an entire cake in one sitting won't lead to anything other than an upset stomach and maybe some temporary extra pounds.
Doing ten push-ups every morning will lead to a stronger upper body down the line. Suffering through 300 push-ups at once won't do much but make you tired.
"Any good coach will tell you that more is gained practicing a short time each day than doing it all at once. Living with it day by day keeps writing on your mind and in your muscles." (Pat Pattison, Writing Better Lyrics)