Few bothersome things are important enough to bother with. It is folly to take to heart what you should turn your back on. Many things that were something are nothing if left alone, and others that were nothing turn into much because we pay attention to them.

Baltasar Gracián y Morales (1601-1658) Spanish Jesuit priest, writer, philosopher

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 121 (1647) [tr. Maurer (1992)]
    (Source)

Alternate translation:

Troublesome things must not be taken too seriously if they can be avoided. It is preposterous to take to heart that which you should throw over your shoulders. Much that would be something has become nothing by being left alone and what was nothing has become of consequence by being made much of.
[tr. Jacobs (1892)]