KD and others,
I would urge you to do some research into "sarcopenia" (age-related muscle deterioration). You will likely come to the conclusion that you should add resistance exercise to your regimen. There are many ways to obtain this, whether weight training, high resistance cycling (I don't mean simply riding a bike, rather, attaching your bike to a magnetic resistance trainer and doing long intervals (4 to 5 minutes each) where you're struggling to stay at 75-80 rpm pedaling cadence, climbing, or other forms. You need the effort to affect your skeletal muscle more than your cardiac muscle. In combination with aerobic exercise you will promote optimal health and fitness, especially as you age.
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B(ern)ank(e)