How to improve 'vagal tone' - 'at home'?

Google search for 'how to improve vagal tone at home?' 

https://www.nytimes.com/2022/06/02/well/mind/vagus-nerve-mental-health.html

https://www.psychologytoday.com/sg/blog/the-athletes-way/202201/how-does-vagus-nerve-stimulation-reduce-ptsd-symptoms

https://health.clevelandclinic.org/vagus-nerve-stimulation/

https://www.forbes.com/sites/womensmedia/2021/04/15/what-the-vagus-nerve-is-and-how-to-stimulate-it-for-better-mental-health/?sh=f90711f6250c

https://www.allied-services.org/news/2020/june/the-vagus-nerve-your-secret-weapon-in-fighting-s/

https://www.brainharmony.com/blog/2021/6/5/15-ways-to-create-vagal-regulation-at-home

https://www.stress.org/contentment-connection-easy-ways-to-nourish-your-vagus-nerve-to-become-more-content

https://en.wikipedia.org/wiki/Vagus_nerve

https://www.britannica.com/science/vagus-nerve

https://www.medicalnewstoday.com/articles/318128#Vagus-nerve-stimulation