Separating boxers into divisions helps ensure fair fights. For example, a fighter who weighs more than 200 pounds has more force behind his punch, while a fighter who weighs 140 pounds will likely be faster and more agile than the heavier fighter.

Boxing isn't an easy sport. In fact, the U.S. Olympic Committee voted boxing as the most difficult of 60 sports in a 2012 survey published by ESPN. Whether you just want to get into shape or step into the ring for real one day, you have a host of options at your disposal for boxing instruction.

Speed bags are an effective tool for training hand speed, rhythm and timing while building endurance in your arms, shoulders and back. Small bags, such as Everlast's 8-by-5-inch Kangaroo bag, moves faster, so it requires considerable skill to control.

Former world heavyweight champion Evander Holyfield is considered a small heavyweight compared with some of the behemoths that populate the division, dating from the early 1990s. Holyfield had to build up his 190-lb. cruiserweight body with a carefully targeted weight-training program to get to 215 lbs.

Muhammad Ali is considered one of the greatest heavyweight boxers of all time. The charismatic Ali ranked No. 3 on ESPN's list of the greatest athletes of the 20th century behind Michael Jordan and Babe Ruth. Ali's speed, quickness and athleticism belied his training style.

Although he is perhaps better known for his fall from grace than for his performances inside the ring, "Iron" Mike Tyson was one of the most formidable boxing champions in the history of the sport.

If you want to start boxing, you need access to the right equipment. You don't have to own everything yourself, but you need a gym that has access to the right kind of equipment to train with. You are best off joining a gym and signing up with a trainer who can teach you the ins and outs of boxing.

Bento boxes are Japanese style packed lunches containing protein, rice and vegetables. The size of the bento box determines the portion size and can impact the total calorie count, as can the food choices you make for your bento.

To keep standards of safety inside the ring, amateur and professional boxers compete in designated weight divisions. Fighters weigh in for a fight 24 hours before they face off, and they must fall within a certain range on the scale.

Hitting a punch bag is a great workout -- not just for your arms but your whole body. Long “rounds” of three minutes will develop your anaerobic fitness and muscular endurance, while shorter “rounds” of higher intensity punching will develop power and strength.

It can take months or even years of practice until you're able to hit a speed bag so it produces a steady rhythm. Before the sound of your speed bag workout can turn heads at the gym, however, you must adjust the bag so it's at the proper height.

Punching bag routines are a great way to train your body to perform boxing combinations. Hitting a bag teaches good form. Punching in combination increases muscle memory. Your body will instinctively repeat the punching motions without hesitation even when you are not hitting a bag.