We can’t get enough when we’ve decided that nothing will ever be enough. We might not make this decision explicitly, but we do make it. And we make ourselves suffer as a result.
The fundamental question to ask isn’t how much is enough but, rather, enough for what? How much money is enough? It depends on how much you plan to spend. How much success is enough? It depends on how you measure success and whether you grade your performance on a curve.
“Enough” is a purely subjective value, so when we cannot get “enough” of something, it’s because we’ve fixed the rules to ensure that we fail. If I have $100 and I decide $99 is enough, I win. If I decide $101 is enough, I lose. Either way, I have $100, but one definition of “enough” makes me a failure and the other makes me a success.
This will sound dumb, but it’s actually very deep: decide that “enough” is just below the level you’ve already attained. Serenity and happiness will follow.