I've spent a few hours playing this game now, and from the very first minute I was missing the option to toggle always run.
Holding SHIFT key all the time (if using mouse/keyboard) or having to press the left joystick (when using gamepad) is extremely frustrating. Not only is very cumbersome, but it also causes tendinitis very quickly.
I don't notice any direct difference in oxygen usage when walking or running, and also I spend the vast majority of my exploring tethered, so it doesn't really matter. Basically this means I want to run all the time. I don't want walking as default movement speed.
Please add a shortcut key to toggle this. I.e. caps lock, or some other key. Or at least an option in the settings. I've had to stop playing this game now it triggers tendinitis immediately in my hand. It cannot be only me wanting an option for this. I tried searching this forums but couldn't find any posts. Googling showed lots of reddit posts etc. with people asking for it.