If someone walks around with the cares of the world on their shoulders, as many fifty-year-olds allow themselves to do, then it will show in their face. They believe that they should 'act their age' and that means adopting the facial expression and body language of what their society perceives a fifty-year-old to be. So of course you're going to look younger if you still insist on using teen body language. And there's nothing wrong with that at all.
I'm 47, hubby is 52. Everyone says we both behave like a pair of kids, and I love it when they say that. Sure, we're starting to get aches and pains, but I think they'd be a lot worse if we were to dwell on them.
Growing old is inevitable. Growing up is optional.