The short version for me, I rode 1K mile/months back when I was 20, then had the first of 8 knee surgeries, and got back on the bike some 30 years later after my left knee was replaced - did a total of 650+ miles on a Giant Suede DX I bought the month before the TKR, and stopped 07-10 due to shoulder surgery. Then the hip started flaking, so got the trike 12-10, but only rode bout 100 miles prior to the hip replacement 06-11.
So I was just getting into riding shape (sorta) and had more surgeries - and had to give up the bike. After 'pining away' about the loss of riding for 30+ years, getting the trike, AND, being able to ride is simply a godsend! So, yes, I do wish for more miles, and more speed - but, the joy of riding is still there for me. I do expect the miles to increase, but the speed? I just don't know.