Sleep, Nutrition and Fitness.
They recon you loose one percent of your fitness per year, after you have reached your peak. There is lots of free high quality information floating around on YouTube about this. Andrew Huberman, Rich Roll and Doctor Any Galpin are just a few that have lots of the latest best practice informative podcasts about all different things. The hardest part is getting time to watch them all and work out the bits that might be helpful to you.
As I have aged the one percentage fitness losses seem to have snuck up on me. I have always just thought I work a pretty physical tradesman job and I must be strong enough for my age but recently I tried doing some deep squats and chin ups and boy did I struggle. I may have been strong at my job but some where along the line with a busy life style I neglected a lot of other full range of movement exercises.
Nutrition is another one I seem to have taken for granted as well. "Because I work and like running I can eat that ever I want" or that is what I used to think and I got away with it for a long time when I was younger, but I slowly lost that lean runners body and put extra kilos on around my waste. It has taken a while to improve my food intake trying to limit the convenient processed food, and eat a bit cleaner, even if it is only one replacement real food item at a time.
Sleep is probably my number one neglection. I have always got up early for work or a run and then stayed up late trying to get all the other things in life done. Again not too bad when your young but nowadays I am achy and sore for longer after a big day at work or a hard workout. They recon eighty percent of your recovery and re building time happens when your asleep.
I have included a few photos that might illustrate my story.
Me in my peak on holidays, with a time of 2:58 in the Honolulu Marathon back in 1983 with bugger all training.
There were definitely some extra unneeded kilograms around my middle on my 14 hour ironman in 2019.
Those strong bike legs above and below was a month or so ago with a lot of loose skin around those old bike legs as I try to eat cleaner, get plenty of sleep and maintain my strength and mobility at a parkrun.