>>76253302
Most of boxing practice is cardio, endurance training, and calisthenics. If you want to do it by yourself, skip rope, run (prefer sprinting over jogging), do squats, situps, pushups (preferably knuckle pushups). Shadowbox by imagining your opponent and punching air, don't forget to dodge sometimes. Get a heavy bag and do 2 minute rounds with 1 minute rest between each other. If you want to join a boxing gym, do the light sparring at 50-70% of your power or so, focus on defense early on.
Gear: choose the boxing gloves by your weight. Buy wraps and learn how to wrap your hands. Get a mouthguard and a helmet (optional) if you're going to spar.
And watch Tony Jeffries, he's very helpful.