*The time you wasted*
The time you are wasting when younger in worry, wrong relationships, laziness, being a couch potato, giving excuses and pursuing meaningless things; you will never get it back.
. *The dreams and talents you shelved*
Are you talented when young; are there things you love to do and you are good at them? Nurture those talents, exploit them, don't give up even if you encounter set backs, don't give up on your dreams. If you give up, when you're older you will look at your peers who stuck to what they love and made it and think to yourself, "That could have been me". Pursue a career, study a course you love. Don't waste years of your life in a field that doesn't fulfill you.