Psalm 138:8

8 The LORD will fulfill his purpose for me;
your love, O LORD, endures forever—
do not abandon the works of your hands.

The belief that God has a purpose for me helps give vision.  This vision is what drives me to walk in the light of the Lord.  I have the belief that I am purposed for something great; that at some point I will accomplish something extraordinary.  This belief helps give shape to my vision, but it does not complete my vision.  I can not even say my vision is complete at this point, and it may not be for some time.  My vision may not be complete until I do accomplish something great, and only then will I know my purpose.

For now I must remain aware and ready for the Lord to work.  I must be patient, and realize it is not my position to know His will and purpose.  It may be decades before I fully realize my vision and purpose.