A man once went to visit his friend who worked at a zoo, there he saw a big full sized adult Elephant tied up in a cage. The elephant was tied up with only a feeble weak metal chain around just one of his legs which was definitely not strong enough to hold him. The Elephant could have easily broken it off effortlessly with a single jerk of his leg.
The man laughed and pointed that out to his zoo keeper friend: " That chain is definitely not strong enough to hold the Elephant, why did you guys even bother".
The zoo keeper friend smiled and replied : "This elephant came to us in the zoo when he was still a small child, we tied him up in the cage with this same chain , initially he tried day and night to get free from the chain he pulled and jerked and fought with the chain day and night but was not strong enough to get free, eventually he gave up and accepted his fate and accepted in his mind that it was impossible for him to break free from this chain, now although he is big and strong enough to break it easily he is still stuck with it. The Elephant is not tied up with this chain, he is tied up with his mind"