I think you are better off talking about stuff that you did in college. If you focus on HS achievements, adcomms will probably infer that you were lazy or unmotivated in college. If you have to discuss some of your HS achievements, do so in a way that downplays the fact that those accomplishments were in high school, either by not mentioning the years/dates that you did the activities in question or by stressing that the activity was something that you continued in your early college years. If your activity was something that can't be discussed in this way -- something akin to being the editor of your high school newspaper or a high school sports star -- then just don't discuss it. It would make you look worse than some kind of wishy-washy essay on your personal characteristics. Adcomms look at people who stress their high school achievements and think, rightly, "What, did they do nothing in college?"
(I didn't include a single one of my hs achievements in my essays or resume ... even though I did a bunch of badass stuff for a highschooler. Instead, I talked about some of my college activities and some personal experiences that discussed junior high, high school, and college.)