I think the problem lies in that word, 'infinity'. We can't really understand what that is. We think of it as a very, very, very large number, because that's all our minds can fathom; but it's not. A number implies a boundary, but infinity is the absence of boundaries. You can say there is an infinite number of increments, but you never reach that; you can never reach infinity. And the increments become smaller and smaller the more of them there are. So if you want to say there are "an infinite number" of increments, then you also have to say the increments become infinitely small...and you can cross over an infinitely small increment. But if you counter that with the argument that you never reach infinity, so you never reach an increment of zero length, then you also have to admit that you can never reach an unlimited number of increments either, and therefore the supposed problem of crossing an infinite number of increments doesn't exist. You can't treat an infinite number like it's a number; you can't have it both ways.