Stretching and aerobics are nice. But they miss an enormous piece of the puzzle. Progressive resistance is the only way to combat the otherwise-inevitable bone loss (and other lean tissue loss): https://www.health.harvard.edu/staying-healthy/strength-training-builds-more-than-muscles
As far back as 2005 various evidence was pointing in the direction that skeletal muscle is part of the endocrine system. That is, people theorized that when you contract muscles hard against a resistance, many other processes unfold in the body with regard to hormones, immune function, and peptide signaling. In 2008 this was confirmed. More theorizing about its role in human health was proposed: https://www.ncbi.nlm.nih.gov/m/pubmed/18923185/
Over the past 11 years, more myokines have been confirmed. There are beneficial signals in the body which only occur when we use progressive resistance. This may be a newly-confirmed area of human biological sciences. But it is confirmed: https://en.m.wikipedia.org/wiki/Myokine
Lifting weights is the cure.