Excuse my (abbreviated) language, it’s meant to be a little bit funny. But it’s also really an important question. I imagine that any one person’s mind would go to one or the other answer quite strongly and it might be interesting to consider the validity of each side. It also takes us to a junction of consciousness of our time.
Some say that happiness is a choice. I believe that it is grace. Perhaps it is a million choices over a million lifetimes, but I don't even agree with that. I don't think happiness can be earned. It is something beyond what could ever be deserved or undeserved. When it comes, the ego says, "I did this." But that is not true. When it comes, if you have known pain to the depths that nothing could rescue you from, the only response is gratitude. In that relief is a sense of awe that most will never know. Seeing happiness as grace is a deep and humble bow.
When we work to balance our awareness on the breath, eventually it falls off. Maybe after one breath, two breaths, or even half a breath. The usual rivers of the mind (neuro-pathways or sanskaras) are powerful. Imagine the Grand Canyon and the Colorado river. All of the rain drops in the area (energy) effortlessly flow to join that river in the pathway that has been carved through time. Our rivers of focus might be anger, frustration, doubt, worry, distraction, analysis - and you might see the ways that subtle thoughts wick through to join a large familiar river that could easily sweep you away.