Any sort of abdominal and low back work will help so some examples would be leg lifts, crunches, mason twists, back extensions etc. Compound movements will also help like deadlifts and squats. Personally something I'm working on and have overlooked a lot when it comes to fitness in my golf is just overall balance and flexibility.
My friend was telling me that improving my core strength will definitely help my swing. Right now, I kind don't do a whole lot of working on the core besides pushups. Anyone have any good tips for improving one's core strength?