When you’re a 20 something, you know you need to be mature because you’ve grown up. You’re seen as an adult, not a kid any more. It’s reality, and you really should face it. The faster you learn the most difficult life lessons, the sooner you can lead a great and successful life. Rich Tatum shared the most difficult things he wished he knew when he was 20 on quora:
　　
　　1.Love hurts, but not as much as not loving.
　
　　2.The friendships you nurture will have a greater effect on your life than where you work or what you earn.
　　
　　3.You are not your job. You are not your bankroll. You are not the sum of your possessions.
　　
　　4.The company does not love you. It has no heart. You are replaceable. Keep your parachute handy.
　　
　　5.Few decisions will ever shape your future life more than who you choose to marry. To marry well, you must choose well.
　　
　　6.Love is a commitment.
　　
　　7.Believe it or not, passions grow out of your values. Make early, wise choices to value what (and who) is good, trustworthy, and praiseworthy.

　　8.Integrity preserved is honor won.
　
　　9.Rejoice in your health. It fades fast.

　　10.Find a passion. Pick a hobby, own it: photography, juggling—whatever. Get your 10K hours of perfect practice in early and change your life.