1. You will make mistakes. You definitely will except you are sitting pretty doing nothing. The great thing about mistakes is that you can learn from your mistake and with constant practice get better. Making mistakes doesn't mean you are stupid, it only means that you have been making an attempt and you are better than those who try to be safe by doing nothing.
2. You will be betrayed especially by people you trusted the most either during a relationship with the opposite sex or with friends of the same sex who you thought always had your back, and as time goes on you'll learn to not trust people so much. You will no longer be as gullible as you used to be because you have become wiser.
3. You will loose friends. People say we have friends for different stages of our lives. We have school friends, church friends, work friends etc. and when we move on to some other place, school or job they cease to be as close as they were and only keep in touch once in a while, but there are particular friends that are part of every aspect of our lives, they know literally everything that goes on in our lives, they are the ones we call besties, buddies and so on. Unfortunately, conflicts and misunderstandings happen in relationships and when you are unable to resolve it, you just might loose a friend.
4. You will wake up from your fantasies and embrace reality. Truth is while growing up we have all those fantasies of how we are going to take over the world without really having any plan in place but as you grow older and weigh the pros and cons you decide what's possible and what's not. You realise that it's not always about you, if you need something, then you must go for it because its not going to be given you on a platter of gold.
5. You will become more confident of yourself. You are no longer that little child who doesn't know what he wants. You now know who you are, your strengths and weaknesses, your likes and dislikes, you've surmounted hurdles that you never thought was possible and it has made you stonger.