ShareThis Plugin: Add Text Summary of Post

Hi there!

I’m using the ShareThis plugin to offer readers a chance to share the post via email, FB, or Twitter.

1) Facebook: It shows the Featured Image and Post Title correctly, and links to the post just fine.
a)Only thing is, there’s no text summary pulled from the post itself. How can I get it to show a summary?

2) Email Share: Shows Post Title correctly and links correctly.
a)It pulls random photos from within the article, rather than the Featured Image. And for some posts that *only* have a Featured Image, it shows no photo at all.
b)This also does not display a text summary of the post. How can I get it to show a summary?

Thanks in advance!!