I agree with the premise but take issue with the measure for "success": do you feel excited to get up and work on Monday?

We're humans and no matter what you're pursuing, you'll hit a point where your brain will adjust to the new reality and things will start feeling mundane. This is called the hedonic treadmill.

To me, what has helped is developing hobbies and relationships outside of work. We're social animals and need connection with others to feel fulfilled. Personally, my own life feels way more fulfilled right now than when I was just working on interesting projects at work or on my startup (that went nowhere).