How should an old monk deal with sexual temptation?

There was a story spread among the Chinese people: there was a mountain in the past, and there was a temple in the mountain. There was an old monk in the temple who had been practicing for 30 years and was about to achieve enlightenment. Below the mountain, there was a town, and in the town there was a very vicious and poisonous rich man who always wanted to destroy the reputation of the old monk.