You can work toward something as a substitute for desiring it. For instance, I think it would be easier for me to write a love poem or even to win someone's heart than to desire them romantically. I could do those things as substitutes for romantic love, and they might be perceived as romantic love, and do some of the work of romantic love, but I would have no such love.
So it can be with holiness. We work toward holiness; worry that we aren't working toward it (a substitute for working toward it); worry that by working toward it, we're bad people for being so ambitious (another substitute); worry that we'll never really be holy (yet another); labor in our minds over it -- but what we could be doing instead is desiring it.