When you choose to start something, you have to train yourself to also finishing it. It is one choice, not two. You chose to start this, so you also chose to finish it.
This was a hard lesson for me to learn and profoundly important in pretty much every aspect of my life. My friends used to joke that I was a “parallel” entrepreneur because I started two or three companies at the same time. I would take on any project without giving much thought to how I would finish it, or how I might be overwhelmed in the pursuit of too many goals. I ended up scattered and unfocused, just trying to keep up with the demands that I signed up for. It was an unsatisfactory life and taught me a crucial lesson. If I didn’t escape this trap, it would have doomed me to a mediocre life.