Pretty much everyone gave you all the advice you need....Make sure you eat before your workout ( about 2 hours before this way it has time to digest and work into the system...Plus make sure you eat high carbs so you have energy to burn)...Like Von said about him going to the gym 3 or so times a week is perfect...only add extra gym time if you have an upcoming fight..Plus drink a lot during workouts..I suggest Vitamin water or gatorade...but not a lot at once just sip it between rounds so you don't get bogged.....Also try to remain standing between rounds walk back and fourth a bit...It helps keep your blood flowing at a better pace and keeps your lungs streached for better oxygen intake...if none of the things the guys here suggested then I would go to my doctor and tell him what you have been doing then ask for him to give you a balanced diet for more energy...Good luck to ya