Here is a simple idea from Jim Rohn:

"You should work harder on yourself than on your job. Because... If you work hard on your job, you can make a living. If you work harder on yourself than you do on your job, u can make a FORTUNE."

And, Jim Rohn also said that this is a simple idea and simple to carry out. But, on the other hand, it is simple not to do it... Simple thing accumulated over years is your current result...