Face it, you're getting old. It'll happen to everyone. I don't even wake up with a consistent hard-on anymore, and I'm a decade younger than you. I mean, if the other half wants to fool around every morning I have no problem performing, but it's not like when I was 18 years old and I had to wait fifteen minutes just to get soft enough to piss every morning. And, I don't use nicotine products (which is a vasoconstrictor, meaning less blood flow, meaning less boners), don't drink excessively, I lift weights six days a week, run six days a week, do intensive core exercises three days a week, and I'm generally in very, very good shape.
We're all just getting old.
By your age, the main culprit, no matter how healthy you are, is going to be low levels of testosterone. I believe after the age of 30 we lose about 1-2% percent of our overall free testosterone levels every year, so by 47 you do the math. But I do have some advice.
Google "tongkat ali." You can purchase it in many shapes and forms in Japan, particularly in the adult section. The pill boxes will usually feature a red tengu character with an extremely long nose. There are a number of brands so pick up a couple. Or, you can shop online at conventional supplement shops like Swanson Vitamins, which I used to order from while living in Japan and they charged a very reasonable shipping rate. Tongkat is basically an herb from southeast Asia and it naturally boosts your testosterone levels.
Back when I was about 27, partially as a joke but also because I wanted to test the effect on my weightlifting, I picked up a bottle and started taking it daily. By the end of the week, my face was getting oily, I was growing zits, my already bad temper went to hair-trigger explosive status and I was horny all fucking day long--basically, I was 16 years old again. I was so pissed off and horny at the end of the day I started boosting my daily runs, one day running so hard and fast for a few miles that I screwed up my knee. And even when I got home I still had to rub one out a couple of times a night (I was single at the time, great timing) just to calm down and sleep.
So if that's what it did to me then, when I was still near my peak testosterone levels, imagine what it could do to you?
You see all these stupid commercials stateside for products like "Ageless Male," which is a pill supplement that supposedly boosts your free testosterone levels and makes you horny and punchy again. Well, they all basically contain the same thing--Tongkat, Tribulus and probably Horny Goat Weed. I'm telling you, just try it. If it works anywhere near as well for you as it did for me, you'll be back to fucking your wife, girlfriend, moderately effeminate Japanese boy at the bar or your favorite tube sock on a daily basis.