Clock press Lean forwards holding the straps (A). Hold your left arm to your chest and extend the right (B). Return to the start and repeat with your other arm. The left-right switches improve your muscle reaction times for better agility.
The chest muscle is a tricky little muscle that for most people just refuses to grow. If you want to fix your unbalanced chest muscle you need a chest exercises blueprint so you would know what exercise you need to do for each part of your chest.
19 Powerful Bodyweight Exercises for Strength and Speed