Today, a good friend added these sentences to my mental toolbox:

...the greatest cause of suffering is unfulfilled expectation. That comes from attachment to things that don't exist, or are passing away. The past is nothing but memories, the future is nothing but dreaming; the present is all there is. If it feels bad, observe it, and it will eventually change. If it feels good, the same thing will happen.

Listening to A tribe called Quest - always worth listening to.