I think it depends on how your mind "works", it's not something that has ever worked for me. I can use grounding techniques, breathing exercises etc and have a variety of ways of calming myself but the idea of finding an internal safe space just doesn't work - it's too close to dissociation for me. I find the assertion that "anyone can" quite dis empowering, in that I end up feeling must be something defective in me that I can't do it. I suppose like everything it's horses for courses - now everything works for everyone.