Fitness Trainer Tim McComsey breaks down two exercises designed to increase the muscles in your inner chest. For these exercises, you'll need a flat bench and two dumbbells.
Lay flat on the bench and grab the dumbbells on both sides of your body. Perform a fly by slightly bending the arms and bringing the dumbbells up in a wide arc above your chest 
until those dumbbells touch. Clink! Lower your arms out at both sides in the same wide arc until you feel the stretch in your chest. Perform 10 to 12 reps before moving straight into the second exercise—the close grip dumbbell press.
With palms facing in and elbows close to your sides, press the dumbbells straight up until your arms are almost fully extended. Lower the dumbbells and repeat for another 10 to 12 reps. 
Perform 3 or 4 sets, until you're thoroughly exhausted.
Once you're done, you should feel a nice pump and more volume in your chest muscles.
