"あなたが一日を管理するのか、それとも一日に管理されるのか"

Simplified Meaning:

Imagine you wake up on a day when you have lots to do. If you plan your activities and stick to your schedule, you are in control of your day. This means you are making things happen the way you want. Now, think about a day you didn’t plan. You might find yourself reacting to things as they come, like missing a deadline or forgetting an appointment, which makes you feel stressed. Here, your day is controlling you. To put it simply, taking charge of your daily tasks helps you feel organized and less stressed. On the other hand, if you wait for things to happen, you might feel overwhelmed and out of control. For example, if Sarah decides to make a to-do list and follows it, she accomplishes more and feels good. If she doesn't, she ends up being late and forgets important things, which makes her feel bad. Taking control of your schedule helps you reach your goals and feel happier.