Elephants
Asking an 8,000 pound elephant to stand up on its hind legs and put all of its weight on the lower abdomen is probably not the easiest task in the world. 

These Asian elephants are highly intelligent and will learn quickly.  However, the hardest part about training is the muscle building program and regiment that they must go through.

Much like an athlete or weight lifter, an elephant must learn and develop the proper muscles needed to do certain tricks.

All of the elephants were born in the wild and have been trained since they were about 3 years old. Their average age is about 40 years old and they can live up to 80 years in captivity, but only about 45-50 years in the wild.