When you do bench press, you don't concentrate on your chest muscles. You have to push the barbell up with your chest. You have to learn it slowly. Otherwise, you have to exercise your arms with your muscles. You have to lean on your chest to concentrate on it. I didn't do much when I practiced the second head. Later, I found out that I lifted the dumbbell with my forearm. Later, relying on my second husband, I made great achievements.