I was doing some "head & shoulders, knees & toes" calisthenics just now. I didn't really feel them: that is to say, I am not yet so fat & flabby, at 6-3 and 290-something, that a dozen quick reps were enough to make me breathe hard or to make any muscles sore.
Then I thought: how about with weights? So I did a dozen reps with a 1 lb weight in each hand. Made an effort to go fast. Still can't really say I felt anything.
Then I did 2 dozen fast reps with a 5 lb weight in each hand. I felt that: my heart and breathing rates were increased for a couple of minutes afterwards, and although it wouldn't really be accurate to say that I'm sore, I can feel a couple of the individual muscles in my back. Not unpleasantly. Just feels like they got a little bit of a workout. Pleasant, actually. I woke those muscles up, and they're glad to be here.
I am not going to try to do "head & shoulders, knees & toes" with 30 lbs in each hand. Not today, anyway.