It took me a while to scan through my head for my favorite age which I would loved to run back to, well I didn't really hold any in mind but I recall when i turned twenty, I had already written a whole down in my jotter and I eventually achieved all of it,....
My 20th year was good, I was ambitious optimistic, I had a small diary were i wrote everything I knew I really started taking my life seriously from my 20th year π...
So it's a year I would love to relive once more....
Interesting what you mention: write down the goals and accomplish them all, it's like a planner. I like that idea and it can work for any age.
Happy Holidays!