Fun & Fitness over 50

I seem to be making some real progress in my cycling ability and I couldn't be more pleased.
Over 1 year of consistent training is starting to pay off.
I've been riding more frequently with my friend Charles and others and I believe it that has challenged me to push harder and also given me some validation that my fitness is improving.
A couple days ago I rode in the afternoon with Charles and a friend of his, Dan. We tackled Powell Hill which was my biggest challenge yet and none of us rode it all the way although Charles has done it before. I was standing on the pedals when they "just wouldn't go no mo". I'm thinking next time to try sitting on the last and steepest section and using the heels down-butt back, glute recruiting position that has been working so well for me recently.
This morning we rode with an old mutual friend Tom who hasn't ridden for awhile because he didn't have a ridable bike. He just bought a Jamis Ventura on eBay, literally yesterday and this was his shakeout cruise.
This ride was a lot of fun. Charles is still tour guide cause he's been riding these roads for 20 years. He hasn't run out of new ones (for me) yet. This was the first time I attempted to ride in a pace line (just 3 of us). I found it a little hairy to sit right on someone's wheel without being able to clearly see the pavement just ahead. I found myself enjoying the hills and pushing harder. I think I have been unconsciously taking it easy without realizing it as I'm getting fitter. I'm not having to work as hard to go the same speed. So I pushed it this time and got that "high" which i realized I haven't had for awhile. Feel terrific.
Charles commented that he's really seen my fitness progress since we started riding together and Tom commented that I was getting hard to keep up with. That made me feel really great!