Warrior Mindset by Michael Asken Phd

If you liked 'On combat" by Grossman, this is even better IMO.

Considerate a little more towards a training manual of psychology in relation to fighting.

250 pages, very well written and documented.

Deserves a place on your shelf.

As we have discussed here before, it's not always the "hardware" but the "software" we see issues with when it comes to this sort of thing.