To be happy, is to never be too happy.
The downside of happiness is that it eventually leads to despair, Because of chemical imbalances, it must come down to its neutral state. so the happier you are, the lower your state of mind will be to balance things out, Making you feel awful. and you notice that when you laugh too much, you get sad. Some things make us so happy that they make us miserable. not only that but it would require twice the effort to reach the same level again in the same period of time.
I think to be happy is to never be too happy, and also suppressing happiness. Just like anger, you are always told to express your anger in a nonviolent way, like exercise. And to never suppress it as it might build up over time.
Not expressing happiness on the other hand is your best bet, as that would make it last longer. however increasing it’s duration reduces it’s quality, but it is totally worth it. The general happiness lasts longer, there’s no side effects of your happiness (no mood swing) which is ultimately what we thrive for.