Building things of lasting value. Raising children. Leaving the world a better place than you found it.

You can get really happy by taking opioids, if you consider happiness to be of primary importance. But happiness alone is empty and not something that we should consider important by itself.

If you don't derive happiness from lasting value, why build it?

If you don't derive happiness from raising children, why have them?

These things aren't intrinsically valuable. You may derive happiness from them, and that's perfectly fine. Or you may derive happiness from rigidly following some moral code, and that's fine also. But there's no "we" when it comes to what one considers most important by itself.