It's fairly easy to fall into a rut. Similar days, work, home activities.
There is something rewarding about trying to learn and do something completely new that we've had no previous experience with. To push ourselves to develop a new skill, study, prove that we can do it.
One of my favourite personal experiences like this was taking a level 2 first aid course a few years ago. I had never done first aid before, and the first day in the class I was completely overwhelmed by the amount of information I was getting exposed to. It required hours of nightly study, daily practical work, in preparation for a rigorous practical exam.
But at the end of the week I found myself amazed with how much I'd learned in a short period of time, and it reaffirmed that we all have room for growth.
So, pick up a new skill. Learn a language, a sport, to program, to paint, to swim. You're never to old to try something completely new and amaze yourself.