If you want a book I personally liked Thomas Hanna's Somatics Reawakening The Mind's Control Of Movement, Flexibility, And Health. It can be found as a PDF on the internet.
The books starts by explaining why you should care about somatics.
He might exaggerate some things but I think that no matter what you do in terms of the factors of aging that Aubrey de Grey describes, if you don't address the somatic factors you won't make it to 300 years of age even if you do gene therapy.
At the end the book describes exercises that you can do at home before going to sleep and after waking up. I'm not sure whether those exercises as described by Hanna are optimal but they do something. There a higher time investment to get into it but after that the regular upkeep is at 5 minutes per day after waking up.
Finding local classes is also good. At the moment I still lack the knowledge to judge the quality of all methods. Doing Feldenkrais with a teacher that has years of experience would be a straightforward route.
Somatics
30 seconds of research leads me to believe it's quackery. Should I investigate further?
This is the question asked by John Cook on Twitter. He lists responses from different people:
Mine are: quantum mechanics, Python, cooking, the language of philosophy.
What learning curve do you wish you'd climbed sooner? Give reasons and stories if you feel like it. Do you think other people should climb the same curves?