How can I improve my Apple Watch Series 7 battery life?

This is more of an FYI, but if you plan on repairing your Apple watch with the blood oxygen sensors, they will likely replace the watch to remove the blood oxygen feature. To send it for repair, you must sign the waiver that says this may be done and you are aware. But it looks like it will be done regardless of the repair needed. I dropped off my series 7, and I was using my older series 5, and they just let me know it would be replaced instead of repaired.

[Re-Titled by Moderator]