If I am understanding this question correctly I believe you are asking for ways in which we can keep our minds active and engaged. There are many ways to do this but I believe the key to keeping our minds active is by challenging ourselves.
By challenging ourselves to complete tasks we have never tried or learn new hobbies and skills we create new connections in our brains which can improve the power of our memories. According to a Harvard Health Publican 7 Ways to Keep Your Mind Sharp at Any Age "Challenging your brain with mental exercise is believed to activate processes that help maintain individual brain cells and stimulate communication among them." I can remember when I learned how to play chess a few years back and I really struggled with many of the concepts. Eventually I got better and still play often online. Today, I feel that I anticipate better while planning lessons or how students may react to learning activities more effectively as a result
Another important factor to keeping our minds active and engaged is rest. I remember in college I would constantly hear of my friends pulling all nighters to finish papers or exams. I found that starting the assignment early and doing it over a number of days helped my focus and overall message. For example, on research papers I would outline and research one day and then come back the next day to begin the writing process. After this I would re-read what I wrote in order to see if my research aligned with my thesis. I found the overall quality of my research papers improved by going through this process.
Ultimately, I believe challenging ourselves and giving yourself enough time to process and understand new skills is a great way to keep our minds "fresh". I hope this helps!
Just as the above answer said, I think challenging one's mind is a good way to keep it active. There are also other ways to keep a mind fresh and active. One good way is exercising. Exercising is good for your health and keeps one's body and mind refreshed. It is good to go outside and exercise. It will freshen and let your mind relax from daily tensions.
Another good way to keep your mind active and fresh is to eat right and rest. Eating protein and healthy foods will improve your health and keep your mind active. People often say before a test it is good to eat protein. This is because it keeps your mind alert and focused. Also, overdoing work is tiring and can be bad for your mind. Even though studying many long hours may seem like a good thing to do, it is not a good thing for your mind or body. Resting is necessary for the mind to stay healthy and fresh. Therefore, rather than cramming, it's better to do this a little at a time.
Hope this helps!