My Ukrainian ex had a worship space in a corner. It didn't have any rugs but had hauntingly beautiful hand painted icons. Maybe rugs are more of a thing in the old countries?
Some churches in Greece and Albania have pews -- the concept was brought back from the North American diaspora where Orthodox parishes were set up in former Protestant or Catholic church buildings -- so you can do all the standing, sitting, and kneeling you might be accustomed too.
Also there isn't a rule against sitting, orthodox churches have seats for people who need or want them and it's absolutely normal to see people sit for some or all of services. It is discouraged to notice who or wonder why.
https://en.m.wikipedia.org/wiki/Ethnic_groups_in_the_Middle_...
As such -- as you say -- changing positions is good for our body which helps us to be more physically comfortable in this magnificent machine. Happiness is God's desire for us, but It has given us the absolutely free will to choose happiness or its opposites. A prayerful life is for personal and societal growth towards selfless compassion for all others, and away from selfish callous disregard for others.