a paradox.................

 The popular adage "use it or lose it" doesn't go far enough.  If you don't use it, you might never gain it in the first place. 

. . . a light bulb went off for me.  Comfort in learning is a paradox.  You can't become truly comfortable with a skill until you've practiced it enough to master it.  But practicing it before you master it is uncomfortable, so you often avoid it.  Accelerated learning requires a second form of courage: being brave enough to use your knowledge as you acquire it.

-Adam Grant, Hidden Potential: The Science of Achieving Greater Things