Paleo diets are all the rage these days but exercising like our distant ancestors also has great benefits. Whether you're lifting heavy things to build your hut or build your biceps, research supports the perks of lifting as heavy as you can handle for short sets. You'll increase your strength and your contribution to the gene pool.
Try this primal workout from Mark's Daily Apple: Grab a weighted object (two dumbbells, sandbag, barbell, kettlebell) and do not put it down until you have completed 3 full cycles of the workout below. Do 1 set of 6 reps for every exercise, and then repeat the entire circuit two more times.