Boxers work hours in the gym to improve at their craft because it's a tough and demanding way to make a living and establish a career.
It could be the toughest of all sports to survive.
Many fighters are drawn to the sport because they love the one-on-one competition and may have seen their heroes emerge victorious in a big fight and they want to emulate that success.
Having that desire is a small part of being successful. You need to have athletic ability and the determination to turn that into fighting skill.
It takes hours in the gym and years to develop the specific characteristics needed to be a great boxer.