This is not very scientific but I think it is a significant milestone in my riding.
It's only been 5 months since I have started. 3 months on a road bike. So the first 3 months of my riding all I was doing was about 10 miles a day for 4 days and one 20 miler on weekends. The last two months I have increased that to 15 miles a day for 4 days and one 25 miler on weekends. So far, that's all I've made time for. I have found a couple of routes that avoids any big hill climbs, although the routes do have hills, just nothing steep and long.
There is this one big, long hill by my house--it is about a 10% grade and is about a mile long. That's long for a Clyde like me! The first month I climbed this hill it damn near killed me! I had to stop several times to lower my heart rate and reduce the pain. When I switched from my MTB to my road bike it was almost like starting over because my road bike has much taller gears and has no granny gear to grind on. I had been avoiding this hill because the few times I did climb it on my road bike I had to stop 3 times!
So yesterday, after 5 mos of hard work and dedication, I decided to tackle this hill I had been avoiding. When I got to it, I immediately switched to my lowest gear (39/25) and spun and spun....well I made it to the top without stopping and without hyperventilating! Wow! I was breathing heavy but I was smiling at the top. A guy walking on the sidewalk must have thought I was going crazy! It felt real good to finally conquer that hill and I just wanted to share.