I find myself on a soapbox once in awhile regarding what is important for us to learn...
In school, I'm not sure I had a singular favorite subject... I loved them all (I know... nerd!)
It is interesting to look back on my few or many years (depending on who you are) and think about what are the most important things that I have learned.
I'll fast-forward to my conclusion..
I wish that I would have learned more about "me." I think that when we go through changes, challenges, and choices in life it seems that it would be nice to know more about ourselves. Our minds, bodies, hearts, spirits. Our emotions, reactions, strengths, and weaknesses. Our likes and dislikes, our pleasures and fears. Our beliefs and morals.
I graduated with a BS in engineering and what I have found most useful in the "real world" is surely not calculations and solutions. No... what I have found most useful is conversations and friendships that have led me to understand myself better. People that encouraged me to follow my dreams and trust myself. People that encourage me to live passionately. THANKS to those people.
So, I did a little internet searching and have some quotes and inspirations on the subject below.

I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived. ~Henry David Thoreau, 1854
“Knowing yourself is the beginning of all wisdom.”
Aristotle (384 BCE - 322 BCE) quotation
Aristotle (384 BCE - 322 BCE) quotation
I only went out for a walk and finally concluded to stay out till sundown, for going out, I found, was really going in. ~John Muir,