What i got from Tolle's explanation of this,is that even while persuing your outer calling,you should still stay in the now,whatever you are doing at the moment,and put your all into that. Which will naturally lead you to the next step. You shouldn't "work towards" a goal,but rather "ride the wave" towards your goal. Make every step into a goal.
This really goes against what the IM/LoA authors write about,they say to visualize your end result and see/feel yourself doing it. With Tolle,its all about what is currently happening.