Full plate was custom fit, which is why a custom suit of armor cost as much as a home back in the Middle Ages. It took weeks to months for an armorer to articulate armor joints to move with the wearer’s limbs and distribute the weight so that it literally fit like a glove and moved with the wearer. The people in my local reenactment group wear full plate, even down to sabutons and they move with great ease as the weight does not restrict them as presented by Hollywood mythos.
My first chainmail byrnie weighted just over 30 pounds and it took a few hours to adjust to its weight but after that, the byrnie was nothing, especially with a belt that took some of the weight off my shoulders and distributed it to my hips, as was done during the Middle Ages. My helmet weighed over 15 pounds, due to safety reasons but I could easily wear the whole ensemble for hours…and often did during large combat events.
The Medieval soldier trained in his armor and professional warriors lived in their armor. It was like constantly lifting weights -Their bodies gained strength and trained to wear and move with armor the way people wear regular clothing.
If anyone here devoted a few hours a day to wearing armor and carrying a sword and shield, it would eventually be no different than wearing a suit and carrying a briefcase.