To live like a cave man, you need to have certain energy expenditures daily when adopting a Paleo lifestyle. Cave men had to be concerned with food preparation, they had to carry firewood and water back to the camp, and they had to build nightly fires where they also sang and danced.
They sprinted, lifted, and walked an average of nine miles per day. Their rhythm was to move a lot and rest every day.
Here's the good part: To meet this need, all you have to do is incorporate movement into your daily routine, or do what you already love, at a lower intensity pace. For example, if you like to hike, go for a hike.
If you like to walk, bike, or swim, do those things; just enjoy what you do while moving. Playing with the kids counts, carrying groceries count, walking up and down the stairs counts. You just have to be conscious that your body needs this movement and be sure to get it every day.
While doing what you like to satisfy your living Paleo cardio requirements, your heart rate should be at about 55 to 70 percent of your maximum. You can figure out your heart rate by simply listening to your body. You shouldn't be huffing and puffing. If you are, you're doing too much.