Not to think of it is the panacea for sorrow. By thinking of it, one can never remove it; on the other hand, by thinking upon sorrow, one only increases it.
भैषज्यमेतद् दुःखस्य यदेतन्नानुचिन्तयेत्। चिन्त्यमानं हि न व्येति भूयश्चापि प्रवर्धते॥