100 pounds was about what my daughter weighed when I stopped carrying her upstairs to bed when she fell asleep in the living room.
These are the kinds of things parents do for their kids. I remember when Beth was little and would wake up frightened in the middle of the night, I would let her sleep with Michel and I would go sleep in her little bed. Struggling up the stairs carrying your little girl to bed is just what you do as a parent. It comes from love and a desire to make life a joy for your child. I don't think it is easy to describe to someone who isn't a parent but I never met a parent who didn't understand it immediately.