There is tons of advice all over this thread, Many roads lead to Rome as they say. But with you looking at osteoporosis it’s time to start lifting

What worked for me was barbell training. The four compound lifts are by far the best bang for your buck, a simple program based around those and eating with intent took me from a lifetime as a skinny guy at 165lbs to over 200lbs and very strong and stout looking

Download boostcamp, choose one of these programs: Greyskull LP, GZCLP, or 531 for beginners. Start with some conservative starting weights and do what the program says. They will slowly progress you up and get you familiar with your compound lifts. They will have you lifting three times per week, and generally you can get it done in an hour or so. After three or four months You can switch over to a slightly more advanced program, I love the simplicity of 531 BBB. Tracking this all on the Boostcamp app really made me love lifting and watching my progress get better and better as time went on.

Steer clear of bro science, If you want to do any reading stick with the fitness wiki and ignore everything else unless it’s Renaissance Periodization on YouTube