I, too, am stage 4, with cancer in the bones. Specifically the spine, and spots on the hips, shoulder and sternum. Started with PSA of 541 and immediately started Bicalutamide in February 2019, Lupron in March 2019, 44 radiation treatments starting in July ending in September 2019. We got PSA down to 2.2 at ond time and then it started to rise again getting to 46 or so, PET scan showed the progression to the bones, started Enzalutamide in March 2020, PSA dropped to 20 but then rose again to 30 in May. Bone scan showed no progression in the bones so we will now see where it goes next Thursday.
As for lifestyle changes, I am easily fatigued, I try to walk once or twice every day with a mile being about my maximum range. Hills or upgrades are difficult. I try to stay active in the woodshop. Above all I try to stay positive. This is a long, tiring journey and some days are easier than others. It helps to know others are on the same journey, we are not in it alone.