That said, I think self-reflection is fantastic. Maybe you feel like you're always running in place? Write down what you've been doing for the past few weeks/months/years, figure out what you think has been valuable or not as valuable, and adjust going forward.
This practice has been super-helpful for me also as a morale boost going into negotiations about compensation. It gives me both moral courage that I have been valuable as well as specific details that I can bring up to demonstrate how I've provided value to the company.
In all of this, though, beware that we tend to undervalue the contributions of others just as much as others undervalue our own contributions. Even for the smartest/most productive of us, our own accomplishments still stand on the shoulders of others'.