Standing up for 30 sec

Before our 11 months old starts standing up completely, I must write that he is making all attempts to stand for like 10 sec then 20 sec, I think the longest I have seen is almost 30 sec. It's really funny, I notice the moment I tell him, look Arnav you are standing, he gets all aware and sits down:). This is been happening from almost when he was 10 months.
So I decided not to make him notice that he is already standing.
Sometimes its so funny to see him when I say "let's stand up" and he will stretch his hands like titanic movie and then try to stand for a while and then sit down again on other occasions the moment I say "lets stand up" he would simple fold his legs so he can sit:) I just don't have any picture of these will post when available.