I think this is basically similar to the ideas of Stoicism. Happiness itself is fleeting, it will come and go, you can't really aim for it, we are awful predic

I think this is basically similar to the ideas of Stoicism. Happiness itself is fleeting, it will come and go, you can't really aim for it, we are awful predictors of it and as you state it's an emotion so it comes an goes. However we can strive to achieve a certain comfort, or tranquillity from knowing that we did our best, that we did what we could and what we should and gain a certain satisfaction from that. That is much more rounded, it's more achievable and stops you from being at whim to the randomness of the world and your own moods.