In March I started swimming much more due to injury. Swam 250k yards in 3mo. One session was 10k in the pool.
Getting past the boredom is a skill. In my experience it’s mostly a symptom of not focusing on your form. Don’t use a watch and count yourself to stay focused. Break it up with challenging blocks to force you to focus. For ex: 50yds on 1min will force you to move and then focus on recovery.
I now really love swimming, which is a shock.