Coding is fun!
In fact, it's so fun that I made a career change to pursue it full time. For years I worked as a systems administrator in the IT field. Over time, what was once a fun line of work morphed into a less creative "daily grind" sort of career. I found it hard to maintain my passion for IT work, especially since I always tinkered as a developer for smaller local clients or personal interest projects.
Eventually I reached a point where I felt competent enough to make a change. Doing so remains one of the single best decisions I've ever made. I am back to working with excitement and passion and have no regrets.
Learning is fun!
...and a requirement. Regularly. Always. Web developers are constantly learning new things. There's often a new JS framework or build tool or pattern to learn. Simplicity in web development is dead. Just 10 years ago, I could never have imagined how developers would choose to navigate the limitations of HTTP. Looking back, I realized we as developers must stay informed about our market, specifically with regards to best practices and which platforms or languages are winning or losing. This requires dedication and a lot of time. If this sounds terrible to you, then I would guess you don't build web applications. For me, it's everything!