Read up on Primal Blueprint exercises if you haven't already. It doesn't take much: 1)Staying active. Lots of slow movement. Avoid sitting for more than an hour. 2)Resistance work. Can be body weight resistance. Mark has beginner exercises. 3)Sprints. These do not have to be running. I can't do that and maybe you can't either. They can be anything that gets you out of breath with your tongue hanging out. Maybe your Gazelle. I had to google to see what it is. If you can get up to sprint speed. 30 second sprint as fast as you can go. 90 second recovery. Repeat for a total of 8 reps.
The treadmill won't be of much use except for walking or light running on days you can't get outside. No need for running on Primal except in sprints and for play.