Doing what I want to do is not on the same plane as doing what I need to do.  If you go through life doing only what you want, then what you get may not be what you really wanted.   What you want is fine, if you have conditioned your character to always want what is best.  The mark of holy character is that we have come to a new natural, where we want what He wants.  Our desire is lost in His desire, and we are happy about it.

 “I delight to do Your will, O my God; Your Law is within my heart” Psalms 40:8 (NASB).