Fun & Fitness over 50

When I first started cycling about a year ago, I sort of had the idea in the back of my mind (sounds better than semi-conscious idea) that as I continued to ride it would get easier. Climbing hills would get easier and I would go faster with less effort. I guess that's true more or less but I don't have easy rides these days.
The other, I think, more significant aspect of getting fitter is that you can tolerate hard effort for longer durations better.
So, yes, while it is easier to climb the same hills I did a year ago and to ride 10 mph like I did a year ago, I find myself tackling harder, steeper and longer hills at a greater effort and kicking my average speed up on rides but overall putting in a higher intensity of effort ... and enjoying it more. I have to keep working harder to get that cyclist's "high".
Does that sound like addiction?