tomarctus: I keep thinking of new things.
Once a man is past 40, and certainly 50, lots of conditions can start to appear, "men's problems". Enlarged prostate, reduced blood flow to the penis, erectile dysfunction, frequent urination, urine leakage, loss of libido, hormone changes. I strongly believe in getting prostate exams at this age, no matter what. If you experience the other conditions don't be shy and don't wait to get them addressed. Sometimes it takes awhile to track down the cause of the problem. It can be illness, medication side effects, hormonal, depression or stress. Just don't wait.
My problems started when I was only 46 which I don't consider old. I have friends in their 70's and 80's who have no problems with sexual performance, so I'm not ready to have 30 dry years.