25 Jumping Jacks
25 Sit Ups
25 Squat Thrusts
Sometimes, people are doing stuff that won't necessarily make them any functionally fitter. Like a door that isn't a door. Walking on a treadmill is fine if your rehabilitating, or if you live in Maine in the winter, and your lungs will freeze if you step outside. But wouldn't it be more than a bit better to just step outside and go for a walk. Unless you live in flats of Texas, there should be SOME terrain that you will walk over that will vary during your outing. Your legs actually work differently when your moving yourself across the ground, as opposed to the ground moving underneath you.
So, if you want to be more functional in your life, do the most functional exercise. Oh, yeah, you already are, 'cuz you're a CrossFitter!