Good morning, Steemians!
Have you met a sad, depressed successful person?! I don't think there are much of those!
Someone may be constantly sad AFTER being successful for some reason. That's life. But I doubt someone becomes successful by being sad all the time. Happy people make things happen. Important things. Happy people can make plans properly. Happy people have goals. When they don't achieve them, do they get sad? Yes, but it's temporary. Soon after they are smiling and trying again.
Joy is important because it's more like a consistent state that you can work on. You depend more on external circumstances for happiness but joy... that's on you!
Go make your life wonderful!
RMach