Come back to the breath. He compared it to the beginning of the rainy season in India. When you do it right, it can clear the mind, refresh the mind, wash away all its dust.
"As the Buddha said, when you get involved in other meditation topics, unskillful states can sometimes arise, in which case you should always come back to the breath. He compared it to the beginning of the rainy season in India. During the hot season everything is dry with lots and lots of dust in the air. But when the first rains come, they wash all the dust out of the air and leave the air very clean, clear, and refreshing. The same way with breath meditation: When you do it right, it can clear the mind, refresh the mind, wash away all its dust." ~ Thanissaro Bhikkhu "The Breath All the Way" (Meditations6)