When you want to say that some action is difficult, you say "it's hard to ___":

It was really hard to hear what she was saying.

It's hard to know what to do in those kinds of situations.

In the example at the top of this post, "it's hard to ___" was re-ordered to "how hard it is to ___". That's because it was used in the expression "you'd be surprised how ___ it is to ___".