Thanks @khimgoh, and sorry to hear about your broken ankles! I've always had weak ankles (I've had an ankle fracture too). I used to run regularly, but found it increasingly difficult when I became hypothyroid, so I started doing long-distance walking instead, and then hillwalking. The hillwalking has definitely strengthened my ankles.
I think any weight-bearing, strengthening exercise is fantastic for people at any age, and it really helps if you love the type of exercise you are doing! I just love climbing and bouldering, and I also do yoga, which can be very strengthening too. @exercisinghealth has recently done a couple of excellent videos on core strengthening:)