The title quote tells you the importance of your attitude. The remarkable thing is that you have a choice every day of what your attitude will be. You cannot change your past, the actions of others, and the inevitable. The only thing you can change is your attitude. That is why it is more important how you react to your life than what happens to you.
I learned of the quotation in March. It was the period in which I was depressed as I had to cancel a lot of my plans for this year and stayed at home safely as more and more people were confirmed Covid-19. Moreover, I was not a person who gets energy at home but an extrovert who is motivated from outside. Consequently, a lot of negative feelings came to me because I was not able to go out and I just blamed it all on the circumstances. One day, I got a message from one of my best friends sharing the quote. It reminded me of the importance of mental attitude. After that, I changed the way I think. I decided to focus my energy, develop myself, and appreciate all the time that I can use to concentrate on myself. I hope you also think about things you can handle, not regarding things you cannot do because of situations.