When I compared several uses of "one day at a time" I get to realize that it means خطوة خطوة و بشكل متواصل as اسكندراني suggested خدها وحدة وحدة
E.g.
Make a note everyday of your successes and your obstacles, then look to your own memories on how to overcome those obstacles. And you will notice that one day at a time you will be tracking your progress, inch by inch moving forward, building momentum until one day you look back across the pages of your journal and you realize how far you’ve come
Why should the holidays be any different? If you want to lose weight this month, you can. You just have to choose to stay in control, one day at a time.
If you only work hard on the days you feel like it, nothing will ever get done! Commit yourself to excellence every workout. One day at a time. Over the entire offseason your progress will be amazing.
Then I will be comfortable to translated تابع (راقب) باستمرار تحسنك التدريجي