Body language: https://www.youtube.com/watch?v=ptgqVgtFEI4

Mental stim: https://www.themoderndogtrainer.net/mental-stimulation-ideas-for-dogs/

Stress: http://www.doglistener.tv/2015/05/stress-in-dogs-what-we-cant-see/

Methods of Teaching: https://www.whole-dog-journal.com/training/advanced-dog-training/how-to-get-a-dog-to-behave/

Find a trainer: https://www.ccpdt.org/dog-owners/certified-dog-trainer-directory/