Two years ago, at age 62, having earlier had a heart attack and then
recently discovered I was diabetic, I decided to retire in order to
prolong my active life. For the first year I just enjoyed not having
to go the office, and took no specific exercise beyond my habitual
approx half hour a week cycling to local shops. I was also rather
pre-occupied with learning how to get my pp BG spikes down and if
possible reduce my neuropathy (it was possible).

This last year I deliberately tried to improve my cardiovascular
fitness by more often doing shopping etc. by bicycle. That averaged
out at around an hour's cycling a week, i.e. an extra half hour a
week. I have one of those bicycle computer things, and always log the
time and distance data to monitor progress. I've got cycling data
going back over the last ten years. Over the last nine and a half
years it shows a general gradual decline in fitness, punctuated by a
couple of severe drops caused by health problems. Doctors tell me this
happens as you get older :-(

Since I started making a point of cycling the extra half hour a week
in the last six months my cycling fitness has been steadily
improving. Last week it got back to the fitness of ten years ago,
before I got knocked back by overwork, age, and health problems. That
was no remarkable state of fitness, but it was very pleasing to be
able to recover pre-diabetic performance levels and imagine that in at
least one respect I'd got ten years younger :-)

Rummaging through my exercise records I discovered that in January
2005 I measured the response of my heart rate to a precise benchmark
exercise of doing 100 full bodyweight-only squats (i.e. right down
until bum on heel) in 400 seconds. That raised my heart rate to
135bpm, and I was close to being falling-down knackered.  So I tried
doing exactly that same exercise again. This time it raised my heart
to only 105bpm! And I wasn't tired, felt as though I could probably
have done another 50!

Wow, there's an improvement!

But wait a minute -- at that time in 2005 I was 10 pounds heavier!
(You see the advantages of keeping records? :-)

So I repeated the exercise several hours later carrying 10 pounds. And
this time by the time I reached 50 I was feeling as exhausted as at
the earlier 100. By the time I reached 100 I felt the same as I did in
2005 at 100. And this time my heart rate was 135bpm, same as in 2005.

So. no improvement? Well, not quite, because hanging onto 5lbs in each
hand is a bit more effort than carrying 10lbs well distributed in
body fat, and several hours wasn't quite enough to fully recover from
the previous exercise.

There's also the important question of recovery rate: how quickly does
the post-exercise elevated heart rate drop in the first two minutes? I
have a note from somewhere suggesting that >20bpm is good, and <12bpm
is bad, see a cardiologist. This recovery rate is significantly
diagnostic of heart attack risk.

In 2005 my recovery rate over the first two minutes was 18bpm, whereas
today it was 30bpm. That's a 50% improvement which suggests a
significantly reduced my heart attack risk. All done without drugs :-)

So, although cycling about the city for about an hour a week instead
of half an hour is a pretty mild form of exercise increase, it
nevertheless has had significant measurable benefits. I also
discovered to my surprise just what a considerable difference losing
just 10 pounds makes to carrying my bodyweight around. Interesting
that with the extra 10lbs I felt as fatigued in terms of heart and
legs at 50 squats as at 100 without them.

Having bothered to do all this arithmetic, I'm now much more
pleased with my progress and much more motivated to keep going. Just
like keeping detailed BG records, it makes it much easier to monitor
progress and keep motivated :-)

Last but not least, having told the good people of asd about this
progress, it's now going to be more difficult for me to backslide :-)

Of course some folk here do more exercise before breakfast than I do
in a week, and others couldn't do it in a month, but the point is that
I took a pretty small amount of cardiovascular exercise (half an hour
a week), doubled it for six months, and got substantial benefits.