No magic answer here but I tell you what I do.

Getting very close to 60. So, I am not getting any younger nor healthier. In addition to the great advice of getting fit, I think that since we cannot get as physical as we were before , it is the more imprtant to get "better mental health" than before. It is still possible.

I used to be hot tempered before, getting upset about so many things that are not "right" either at work or at home. Now , I take it easy and try to be more focused on what is most important , shoving less important things a little behind.

For example, a few things at work are definitely wrong (IMO), but I have figured that if they weren't fixed in the last 20 years , they won't be fixed now, so why bother?? I better get more focused on thing that I CAN do , like gardening..... Speaking of which ... I can add the advice/suggestion : get yourself a useful, productive hobby that can help your mentality as well as help you in case of SHTF.