short answer: by hating yourself   long answer: you gotta get your bodyfat percent down to 6-13% for your abs to be visible. I do bulking and than defining, which means i first gain muscle by weight training and eating more calories (but also gain a bit fat too). Then proceed to do a calorie deficit diet and cardio for fat loss but maintain the muscle by keep doing strengh training. I also do sit ups with weights because higher weight, but less reps helps with hypertrophy