I had osteoporosis before breast cancer and a fracture so as well as being on Femara / Letrozole I have 6 monthly Prolia injections to counteract bone loss - there also tablets called bisphosphonates available to build bone which I recommend careful thought before starting. . I also take 2 Caltrate Bone Health tablets daily - 1 morning 1 evening. I get some joint pain but walk daily for an hour - not always easy but seem to be able to walk thru joint pain knees , hips etc.I also a gentle exercise class Stretch/Balance twice weekly which amongst other things involves light weights and I think it helps my bones.There is also a free YWCA hydrotherapy course for bc ladies which I have found helpful - it’s 8 weeks , 2 hours weekly and can be done up to 4 courses but must be 12 weeks post op.
One of the ladies on here is reporting wonderful improvements in bone density thru an exercise program run by a Uni involving weight training.I did not have chemo just radiotherapy and both cause bone problems I gather.But there are things that can be done to counteract it , bone density should be monitored during treatment with aromatase inhibitors as well as the outset to give you a baseline.