Im not sure if you experience this but what you describe sounds like depersonalisation ( I might be stating the bloody obvious) I get this a lot walking along like I'm on someone else's back , my limbs don't really belong to me , then a little panic sets in and everything becomes hard work , heavy limbs breathing becomes harder which in turn reduces oxygen to the muscles and it makes it even harder , my mouth is always a step in front of my brain as well but that's a different storey .
You also do what I do over analysing everything why am I feeling this way must be a reason but sometimes there is no reason and questioning it just makes it more of a problem .
One thing I do know is trying too hard to be in the moment takes you out of the moment if that makes sence , if im feeling spaced out and weird doing something you have to concentrate on brings you back into the now .
Lifting and carrying is an issue with me as well , if I need to move something heavy I've already overthought it before I start and doomed myself , getting out of breath and not getting it back is my fear so starting to get out of breath sets in the panic , if I just have to do something on the spur of the moment I'm usually ok .
Turning into a bit of a cuckoo sneaking into other people's threads while they are out I really need to stop that , 4000+ views so people are reading .
Take care