Diet and exercise are great for so many reasons, and will lower your cholesterol some.

HOWEVER...if your genetics cause your cholesterol to be EXTREMELY high, the the modest benefits obtainable by lifestyle factors will probably not be able to lower into a safe range. Don't hesitate to do the meds if that is what you need to do. I had a very good buddy keel over dead from a massive MI..he was in his early forties (with wife & kid), EXTREMELY fit special ops guy who ran marathons and ate well. He had high cholesterol and didn't want to do the meds so he tried to manage it with lifestyle...not good enough in his case