This is a great notion to keep in mind whenever we feel overwhelmed by a goal or challenge. In Venezuela we have experienced this the hard way.
Some years ago when public transportation was as good as in any other Latin-American country and probably better than some, we saw walking certain distances in town as hard and unnecessary, especially given our perennial hot weather.
Now that we have few busses and cars circulating, and we have no choice but to walk from one end of town to the next, we realized that even if it takes you 3 hours to complete the distance to run the errand, you walk that distance one step at the time, one block at the time.
Now people challenge one another as to who has walked the farthest.
Of course, there is no much to feel proud about here, but I think it serves as example of mental conditioning and lowering of the anxiety to carry out a project.
I like the notion of marginal effect. Had used it with my students without knowing it by its name. Every time they complained about my reading assignments I asked them to do the math. When they realized that the time they had to devote to reading for my class was actually less than the time they spent on busses on a daily basis or less than the time they used on social-networking they stopped complaining.
Of course, most of them rarely sacrificed their not-to-do-anything time or their Facebook time for some stupid American author, anyway.