I appreciate that I am lucky because many can not do what I have done but I am a massive believer in exercise.
I was diagnosed aged 49 T4 n1m1a, now over 5 years on I have run ultramarathons all over the world. The most recent in the African jungle, 200 k over 6 days. I have run every day for the last 77 days too. I ran over 3000 miles last year, I will run more this year.
i am a plodder, I never will win anything and come about half way down in any race but even if you walk there is great benefit.
There is a fair bit of science around exercise producing antibodies that attach themselves to damaged cells when exercising. A common incorrect belief is that they reduce after exercise, they don’t reduce but are in fact hard at work repairing damaged cells. I have had virtually no colds or sickness etc in the last 5 years including when I was on chemo, I am fitter now than I have ever been with cancer ( and remain incureable) . My PSA has gone from 342 to 0.15 where it has stayed for over a year. There is even evidence to say exercise immediately before a flu jab increases the success of that jab.
i also go to the gym, never had any upper body strength but changed what I do and am now growing muscle again. I have also lost 10 kg since last August.
My diet is predominantly vegan however when I go out I eat what I like ( meat/dairy/eggs) and do eat fish at home.
impact exercise is also good for your bones as the impact effectively slightly damages the bones and then the body fixes the damage and some.