I would second this. I took up bouldering and it's amazing how much more energy I have. My lower-back pain from sitting has nearly disappeared.

It's a true full-body workout (including the brain).

I would add buying a kettlebell and starting to do swings and Turkish get-up. They're energizing and work almost your entire body in a functional way.

I'd add hiking or running to this. I've seen my coworkers get winded walking hilly sidewalks, any type of ambulatory work is at the heart of human function.