Fun & Fitness over 50

Sunday, I rode my longest ride yet, 35 miles. You see, I'm training for a half-century on June 8th by increasing my weekend "long" ride by 5 miles per week.
Yes, I know this is not a long ride by most of you experienced rider's standards!
I did my favorite 25 mile Sunday loop plus an extra lap of my 10 mile daily ride.
It was such a beautiful, wind-free, sunny day and I felt so good near the end of the 25 mile loop that I decided to go ahead with the extra 10 miles.
I pushed it a little harder than usual too. Stood up in the saddle more and used higher gearing on some of the hills.
I love that 25 mile loop. It has enough hills to provide a good workout but doesn't have any long, killer grades that grind me down. It's scenic and varied enough to be interesting. It provides enough variety of terrain and scenery to have many good milestone markers to look forward to. Much of the ride is through very low traffic rural areas. I may not see a single car for many miles, especially because it's Sunday.
Still, my average speed was only slightly above 10 mph! I'm trying to get up to "touring" speed, 14-16mph so I can do some group rides with the local bike club. I'm riding a relatively heavy cro-mo steel rigid "mountain" bike with knobby tires. I'm hoping to be able to get a road bike soon and that that will enable me to improve my speed significantly on these rides.