What brings us happiness? A balance of mastery and challenge. This is a paradox as a life with only mastery and no challenge would be boring. Imagine playing a 3 year old in a game of checkers. You would always win and there would be no challenge. But a life with only challenges and no mastery would be equally, if not more, dreadful. It would be like constantly getting sand kicked in your face. And just when you’re about to get up again, someone shoves you down. A life of only challenges yet no mastery is not a life of happiness.
We need a balance between the two. With mastery brings a sense of accomplishment and of overcoming difficulties that not everyone is willing to attempt. But if you only stay within your comfort zone, in the domain which you have mastered, you will soon find yourself bored. And a bored mind is not optimized for maximum happiness. Instead, you need another challenge, something to take you out of your comfort zone, but a challenge that is still possible to overcome. And then the cycle continues, as anything that challenges you is inherently something you have not mastered yet.