Crossfit can be intimidating for some, motivational for others.
I would recommend starting slow. Most major cities have ClassPass, which allows you to visit many different gyms and classes per month. Find one you like, or an instructor that you like, and be disciplined about it.
As you can tell by my handle, I go out and run 3x a week. It's a great way to get outside (even though Los Angeles is quite polluted) and out of the office/car/apartment grind.