"Walking is martial arts"
What this means is that no matter what sort of physique you have, you can do Aikido. Whether you are rigid or soft or thin or heavy set, you can do Aikido in your own way as long as you find the way to move that's most natural for yourself.
In other words, you must continue to improve your physique so that it is not forced but natural. You could say that this is the unrelenting struggle of shugyo. So, if you develop the physique that is best suited to your age, you will be able to do Aikido forever, no matter how old you are.
I rarely read poems, but digging my historical notes, I’ve found this link to “The Raven” by Edgar Allan Poe, illustrated by Gustave Doré: https://ebooks.adelaide.edu.au/p/poe/edgar_allan/raven/ Overwhelming illustrations!!! For Simpson lovers – “The Raven” in their way: and the full text for lazy people: Edgar Allan Poe. The Raven Once upon a midnight dreary, while …