I am trying to figure out how to bring out the lower cut of my chest all the way up to the armpit. My chest looks full from a front view, but when I flex from the side view you can really tell there is a lack of muscle right there. I am sure declines will help, and I have been focusing on those a lot more the last month. But is there any other excercises that will help me catch that part of my body up.

Any help appreciated!
Thanks.