Decline bench press
Decline dumbbell press
Dips with a forward lean
Cable flyes from high to low
High-to-low pec deck flyes
Decline push-ups
Weighted chest dips
Lower-chest-focused machine press with a slight decline angle
Use a full range of motion
Keep elbows slightly tucked
Control the lowering phase
Squeeze at the bottom of each rep
Train chest 2 to 3 times per week
Progressively increase weight or reps
Maintain low body fat to improve lower chest definition