The first of the 10 commandments requires us to believe in G-d. While it may seem paradoxical to command belief -- the assumption that there is a G-d who commands presupposes the mitzvah -- R' Elchanan Wasserman explained that this is not a question. Belief is natural to any individual uncorrupted by the negative influence of environment. Emunah does that require that we create an inclination to believe in G-d -- that inclination is already there. Emunah requires that we don't undermine and undo that inclination.
R' Shach (Avi Ezri, Hil Tshuvah) writes that he was always bothered why the mitzvah is called emunah, belief, when belief in G-d is actually something that any thinking person can accept as the only rational and intelligent conclusion. The proper word to use should be "knowledge", to know G-d, not "belief" (which is in fact the term the Rambam uses, but which is not the way we generally speak of emunah). He writes that he asked this to the Brisker Rav who also asked the same question to R' Chaim. R' Chaim answered that accepting G-d's existance is certainly a logically compelling conclusion to draw and hence can be called "knowledge", but emunah entails far more than that. True emunah begins at the point where knowledge ends. Emunah means going beyond what the mind logically can intuit and accepting religious truth on faith alone.
It seems to me that if this is the definition of the mitzvah of emunah, then R' Elchanan's answer will not work. Going beyond what the mind rationally dictates is not something that is natural. Perhaps R' Chaim simply meant that there are different levels to the mitzvah: a basic level that is fulfilled based on accepting what is intuitively known to be true to the uncorrupted thinker and a higher level which ranges beyond that (however, it does not sound to me like this is what R' Chaim was driving at -- take a look!)