Welcome the jungle!
Without question, the best athletes on the planet are, you guessed it, wild animals. Think about a cheetah sprinting at 70 miles an hour to catch a gazelle. Remember Shark Week when we all saw a great white shark surging its entire 1-2 tons of mass straight out of the water with a chubby seal in it's jaws? Ever seen a jaguar haul an animal nearly twice its body weight up a tree! You get the point. Wild animals are badass. Ok, but what about humans?
I've heard this from the very best strength and conditioning coaches time and time again, the best athletes on the planet are gymnasts. Their functional strength and stamina is just unbelievable. The key differentiator between gymnasts and let's say a powerlifter or a CrossFit athlete is their enormous strength in dynamic positions in relation to their own body weight. And when I say dynamic, I mean holy strength and flexibility!
In fact, many great athletes today doing superhuman feats come from competitive gymnast backgrounds (like the first girl to ever complete an American Ninja Warrior obstacle course or the recent winner of the women's CrossFit games).
Carefully consider the following...gymnasts use virtually no equipment other than props to leverage their own body weight (like a chimp leveraging a tree). Just like wild animals, gymnasts get into elite shape in relation to their own body mass and its full dynamic range of movement. They don't exercise within limited fixed positions and thus this style of training is incredibly effective, crossing over into day to day life and activities of daily living. Life is not a bench press folks.
So, to build some great functional strength, let your own body weight provide the resistance, you're heavier than you think (just kidding...not really). You'll be surprised at how agile, limber, strong and dynamic your body will become.