I asked Walter about a basic exercise I could adopt without buying a lot of equipment. He suggested the "get-up." This is where you get down on the floor and then get back up again. It helps, he said, to have knee pads.
I remember reading about this exercise many years ago, when I was deep into weight training (at least deep for me). This was a favorite of Jack LaLanne, the fitness guru who had a tv show in the 50s. (Jack, age 95, just keeps on ticking: Exhibit A for his methods. And he is a vegetarian. I want to be like him when I grow up.) Here is a description of Lalanne's get-up.
There is something called a Turkish Get-up, that looks like a modification of the idea. It involves a kettle-bell or dumbbell. I like LaLanne's approach much better. And besides, there is less chance of knocking your teeth out when the kettle bell slips.