Such a great question! And the exciting part is that you can do ANYTHING! But maybe that feels a little overwhelming, doesn't it?
So, here's my question for you: what do you ENJOY? That's the absolute best place to start.
For me, I started with about ten minutes of walking three to five times a week, and didn't do anything else for about a year. By then, I was ready to branch out and try something new, so I started to run a little bit. Then, a few months after that, I added some bodyweight strength. And then, some time after that, I tried using dumbbells. Over the years, I've ended up building a robust routine that includes lots of different equipment and types of exercise, but I definitely didn't start with that.
The moral of this story: Start small, do what you like, and don't be in a hurry to "get there."
If you'd like something relatively simple to start with, you might like this quick walking workout from my YouTube channel: 10 Minute POWER WALK