A boxer usually practices with a dead weight. He increases his strength and trains himself using the dead weight to fight in the real matches. The fighting practice by the boxer is like working of vaccine. Why?

As we know, vaccines contain weakened or inactive parts of a particular organism (antigen) that triggers an immune response within the body, which is a training for your body so if a real antigen attacks it, it will be trained and kill it with ease. Same thing with the boxer, he is training with dead weight so when he has a boxing match he will be ready and win with ease.

Hold on to his or her beliefs even if there is no evidence for those beliefs.