I've come across 'hard old people' and I usually feel sorry for them. The biggest thing I take away from encounters with angry older folks is that I plan to stay busy promoting a really good attitude in my life so I'll be one of those really happy (probably a bit ditzy!) old folks!
If I learn to take life on life's terms and see and be the good in the world I can't imagine I'll be any different when I'm old. Of course I also believe if you rage at the world your whole life how can you be anything but angry when you're old? Start young I say!!!!!