What is the meaning of ", I dwell on Lisa herself "?

But on this crisp morning it’s hard to focus on running. My thoughts are elsewhere. I think about fresh-faced Jonah Thompson and his annoying tenacity. I think about the article on Lisa’s death and its refusal to acknowledge how what she went through messed her up so much she decided to sink a knife into both her wrists. Mostly, though, I dwell on Lisa herself and what possibly could have been going through her mind when she sent me that email. Was she sad? Desperate? Was the knife already gripped in her trembling hands