Here’s a fun fact. This can actually trigger atrial fibrillation if one is prone to that, as I am. Presumably vertical inversion increases left atrial volume, and stretching the wall of the atrium can trigger the arrhythmia.

I strongly agree to keep up an exercise regimen as we age. As you point out, many modifications will need to be made along the way, and our ego definitely needs to be put in time out. That in itself is a part of gaining wisdom, which hopefully is also part of one’s aging process.