After going through some memory stick, in the back of a draw in the bedroom, I found some old video footage I made with my ex, in my early 30s. Now on those videos, my dick looked larger than it does now, even with the aid of modern pharmacology (viagra & meth or 4-FMPH). Admittedly, after the break up with my ex, I was almost celebate for 10 years (my wife definitely relit the flame of lust and desire).
So, is this just another inevitable headfuck that comes with aging, or has the 10 years of virtually no libido done it (or am I going a bit batshit crazy in my later years)?
Some men become estrogen dominant with age. As you reach your 50's/60's, if estrogen dominance is the case, you will gain belly fat, develop moobs, and your dick will atrophy. You can counter this by getting weekly testosterone injections. Sometimes taking DHEA helps, but DHEA can convert into either testosterone or estrogen, so it's a little riskier.
If your dick shrinkage is due to fatty deposits, you can do a water fast and those will get eaten up. Water fasting is not for the faint of heart, it's a serious commitment, but it will get the body to burn all the body's garbage as fuel, including arterial plaques.
If you smoke, eat a high fat diet, don't exercise, or your T is low, these could all be contributing factors. Just because you're not overweight doesn't mean there's not a high LDL problem going on. You should get your blood lipids tested (cholesterol, HDL/LDL, triglycerides) to see what's going on there. If those are OK, then your problem is mostly hormonal.
Dick shrinkage and atrophy can be corrected with testosterone. I've been on forums where guys messed with progesterone (which antagonizes T), and they ended up with shrinking and numb penises. Once they stopped the progesterone and their T came back, their dicks returned to normal. These were older men too.
You can't make your dick
bigger than it's natural size but you can
maximize its natural size with T.
Erections are partly a function of T, but also a function of nitric oxide. You could try taking L-arginine for a few weeks to see if that boosts NO and in turn your hard ons.