I was fortunate to have the chance to work with intelligent and capable peoples. Those days, I wish I could be like them and so I observed how they do things, but i never figured out how they did so intelligently.
Once i asked my kid, "how did you manage to come out with that solution?" The reply was, "Don't know, just know it!" Just like those prodigies appear in talk show, the common reply is something like "It just appear in my head!". Probably the same, I can't understand why some find Math tough!