My daughter knows I am not able to pick her up from a standing position or hold and carry her while standing.  She does know though that I can pick her up and hold her while sitting.  The other day she was sitting on a bar stool and wanted me to help her down even though she's perfectly capable of climbing down on her own.  When I walked over to her she pointed to a dining chair, wanting me to sit down to help her.  Or sometimes she will lead me by the hand over to the couch or a chair so I can pick her up.  I am often touched by how understanding and considerate she is.  But most of the time, when she asks to be picked up, I will simply just get down on the floor wherever we are and let her crawl onto my lap.  Sometimes, in the middle of preparing dinner, I will stop and sit down or kneel on the kitchen floor to hold her.