...for seriously outta shape 50+ guys who ride cushy comfort (Grandpa? ) bikes and still wheeze and puff their way through a (very) few miles?

Man... it's gonna be a long trip back from when I was in decent shape! No, wait... I've never been in truly decent shape. Ever. Never. It's not that I'm grossly overweight, per se, (being 6' 1"+ has its mathmatical advantages). I just have about zero cardiopulmonary endurance. Not that my legs are stellar, but my lungs give out first. Today, over a seriously embarassing few miles (< 10, far less) I managed to get my pulse rate pretty high and completely winded. A few minutes rest and I was OK, but I guess a few decades of virtual neglect aren't going to go quietly into the night...