This paragraph really resonated with me:
“When we’re living fully, what we feel is engaged and immersed, challenged and focused, curious and passionate. Happiness — or more specifically, satisfaction — is something we mostly feel retrospectively, as a payoff on our investment. And then, before very long, we move on to the next challenge.”

As well as these two…
“It’s about learning to embrace our own opposites. In Good to Great, Jim Collins finds a perfect example in James Stockdale, the highest-ranking naval officer held as a prisoner of war during Vietnam.

Over seven years, Stockdale was tortured repeatedly, held in solitary confinement and given no reason to believe he would ever make it out alive. His saving grace was the ability to embrace both optimism and realism concurrently — something Collins named “the Stockdale Paradox.”

(Source: blogs.hbr.org)