(Denver C. Fox) writes:

Your no-good brother-in-law likely won't be around much longer in
this world, and will bother you no more!

I am 65, and I ride and weight lift and walk because I like the
feeling of being in control of my body and the absolute joy of being
in the fresh outside.

I just came back from a 2.5 mile walk in the sunny snow. Such a
pleasure, and 2.5 miles to me walking in the snow is as easy as a 25
mile bike ride!

However, there are no guarantees. September 1st I started
continuous atrial fibrillation, and have been fighting it ever
since. This is despite my years of biking, walking, hiking and
eating right. However, my heart is otherwise in such great shape
that I can still do extended walks and rides with no difficulty.

There are indeed no guarantees, but staying fit and active really
improves your odds. You can't guarantee that you will have good
health, but you can pretty much guarantee bad health. The OP's
brother in law is on this second path.

Best wishes for a good plan of care by your cardiologist to get this
under control, and many more more years of happy activity!