Wow, thats a lot of info,Ok, this is just me, but, think about it,you just turned 50?And assuming there is no big red S on your chest,give it a break,Now im gonna say something you have to think about for a sec...... (you are more than what you are when just on your bike!)there are other things you need to do, to be good at what you like!Try getting your head around something like this(
http://www.fitnessanywhere.com/index.php) say one hour each,i know its a streach, but just think a bit! good luck, and Enjoy your ride!