1. Adjust your diet: You can't exercise beautiful muscle lines, probably because your diet doesn't achieve enough protein and calorie intake. You need to ensure that you get enough protein every day, and at the same time, you need to ensure enough calories to support muscle growth.

2. Increase the intensity of training: If your training intensity is not enough, your muscles may not get enough stimulation to grow beautiful lines. You can try to increase the weight of training or increase the number of training times to improve the training intensity.

3. Increase the training frequency: If your training frequency is not enough, your muscles may not get enough stimulation to grow beautiful lines. You can try to increase the training frequency by increasing the number of times per week.

4. Keep a good rest: Muscle growth is mainly carried out during rest. If you don't have enough rest, your muscles may not recover to grow beautiful lines. You need to ensure that you have enough sleep time every day, and you need to keep enough rest time between training days and non-training days.

5. Ask a professional: If you try the above methods and still can't practice beautiful muscle lines, then you may need to consult a professional fitness coach, who can give more professional advice according to your specific situation.