How do you know if you're truly happy? That you're working on something not because you feel the need to prove something, battle your insecurities, but rather b

How do you know if you're truly happy? That you're working on something not because you feel the need to prove something, battle your insecurities, but rather because you want to do something meaningful? I'm genuinely curious. Many highly-driven people seem to be insecure and egocentric and in the moment, even long periods, fuelling their ego makes them think they're happy. But if you feel happy for many years (assuming eventually this feeling fades), who's to judge that you weren't happy before? Maybe it all depends on the person, and people can have their pathologies and subconscious desires to better their social status by justifying hustle as working to build interesting products. But maybe that's not it, and the inner motivation is something else?