My dream is to be able to run again. Please. Let me run a 10k at least once more in my life. To feel that stillness and freedom and calm that sets in when the brain start going to hibernation after about 7km.
That would be quiet something to feel that again.
Can you swim? This is the only thing besides running that gets me there.
Hope you see your dream realized. But know that that stillness is achievable through other activities as well. Most directly and deeply, through a meditation practice which is geared towards reaching those deep meditation states (called Jhanas in the Pali canon). My favorite guide on that particular path is Leigh Brasington.