You need systematic training. If possible, you can find a coach to take you to the gym for two months, which is generally no problem (summer 1 month is very easy). If it's not practical, it's simple. First, control the diet to be low in oil, sugar and salt (that is to say, eat as little or no fried food as possible, and the sweets and their own tastes should be moderately light). Secondly, do aerobic exercise at least four times a week (no less than 45 minutes each time). Finally, through simple instrument training, there will be unexpected results. As long as you have perseverance, stick to yourself and believe that you are the best!