This comes from the book called 'timeless seasons' by Rabbi Pinchos Roberts, but I figure most people haven't heard of it and it is SO relevant to us.
How come ALL the Jews, without exception, accepted the Torah at Har Sinai? In parshas Vo'eschanan (Devorim 4:35), Moshe reminds the people that they had been shown with their own eyes 'ain oid milvado'. Rashi explains that at Har Sinai, Hashem opened all 7 heavens and showed the people Malchus Hashem in all its glory. It was so pleasurable and wonderful that everyone wanted in.
It could be that this is what the nations of the world were complaining about, when they said that the Jews got special treatment. If they had seen how good it was, they would have accepted it as well! However, Hashem answered them to bring Him the book of their lineage. In other words, He was telling them that in order to see a Mareh Elokim, they needed pure eyes. This was an inheritance that we received from Shem (who didn't look at Noach), Avrohom (who wouldn't stare at Sarah - see megillah 15a), Yosef Hatzadik, and the people in the Midbar camped in a 'ma tovu' way for this very reason - i.e. not to see anything inappropriate.
In other words, the prerequisite for a proper Kabbalas haTorah is GUARD YOUR EYES!!! How can we daven every morning 'v'hoer eineinu besoirosecho' if those same eyes are tainted with shmutz? We have to make our eyes capable of becoming holy, before the Torah can do its work with them.
In conclusion, we need to guard our eyes becayse it's the only way we can truly connect with our special gift that makes us different from the nations (ve'hivdilanu min hatoyim - venosan lonu Toras emes). And we CAN do it, because we have the strength through our inheritance!