If you walk fast for three hours every day, and then eat and drink all kinds of junk food. . .

Will only become a strong fat man. . .

Eat a light diet, drink plenty of water, plus aerobic exercise for 100 minutes every day, work and rest regularly, and knock on the meridians on both sides of the thigh before going to bed. . .

You didn't gain weight in a day, so losing weight is a protracted war.