My wife and I started P90X at 50 years old and it is a great all around program you can do at home. I'm no monster, but am in decent shape. Modify the workouts to your abilities, stick with it and watch your fitness and endurance grow. I have two bad knees, a horrible neck, a bad disc in my back and troublesome shoulders. The workout doesn't cure them, but it makes all of me better able to compensate for my 52 year old body. Was 178lbs when I started, got down to 163lbs after first year and am happy at 169 lbs now. I'm 5'11" tall.
Do something. Getting older is hard on the body and the brain doesn't keep pace. Still think like a kid. Can't get too old to play.