It's not often I share the secrets to my dad's training regimen, but you need to know about this one. My dad is 72, and I've been training him for roughly six years now; we progress and mix up his plan every few months, and here and there, I like to share some of his favorite strength exercises with readers.
This one requires a set of the best adjustable dumbbells or hex dumbbells if you prefer your weights less bulky. You could substitute kettlebells or heavy water bottles instead. You'll also need an unstable surface like a Bosu trainer, which is affordable online, but can be replaced by wobble boards or similar.