I'm sorry I was so brief but yeah, I meant the second way Tiny explained.
It also helps if you can bring your outside leg forward and give that leg closer to the girth, I've actually gotten to the point where I've kicked my foot out of my stirrup and literally pushed their shoulder back in by reaching my foot up there and giving it a boot, but I don't reccomend that one XD.
You need to think: shoulder up, hip in, and inside hind leg up and under.