Know thyself has been one of the best pieces of advice out there. Finding what there is within you is vitally important to your happiness.
What things are you good at?
Everyone has a talent of some kind. Finding it can be a challenge sometimes if it is not obvious. It isn't enough to just know what your talent is but to take the time to hone it and perfect it. Far too many people who have a talent don't develop it as much as someone who isn't as good but has more desire to get better at it. Those people who take the time to perfect themselves, do the best and that makes all the difference.
How you deal with your strengths and weaknesses is an important factor in how well you do in life. By strengthening your strengths and understanding your weakness you can get far more done.
Say you want to start a business and you are good at making chairs. Making chairs tends to make a lot of sawdust. Now it is fairly important to get the sawdust out of the way from time to time. It can interfere with the tools and become a fire hazard. But if you are not good with a broom, then hiring someone to clean up the dust from time to time can free you up to make more chairs more quickly.
If, on the other hand you have weakness that is interfering with your life, an addiction or something that someone else can't do for you, it is important to for you to grow by confronting it and overcoming it making it a strength.