I'm 61 and do the treadmill. I do interval training by starting out at 2.5 for 2 minutes, then increase speed and incline every 2 minutes. When I get to the point that I am sweating and it's hard to talk, I stay for 2 minutes, then take it back down to 2.5 then gradually increase again. I do this for 30 minutes.
I also use the Bollywood videos here on Sparkpeople.
I have a dog that needs walking, and grandchildren that love to dance.