@Twiglets, your post is really interesting. Some of those things I sort of did last time I had my transfer/got my BFP.
Whilst I didn't 'practise my breathing' per se, I did make a point of taking a garden chair out to the blossom trees and sitting there peacefully for half an hour a day.
I also went for a gentle walk every afternoon (and sometimes in the mornings too.) I had some back pain at that point but allowed myself to sit on people's fences to regain my composure (not that I was racing around, but I was just exhausted because...well...it was early pregnancy!)
I ate pretty much what I felt like but omitted the usual nasties - soft cheeses, shellfish, runny yolks etc. And I washed everything (like salad leaves) extra well. The cat litter was a no-go zone, but for the main part I just tried to relax and enjoy the experience. It was such a nice time for me - until it fell to crap. But that's another story.....