i used to box but ive been getting lazy lately,how long have you been doing it? i did it for about 3 years.it kinda loses it's thunder after that long but for me it wasnt really the boxing as much as the meditating while i did it,very enlightening,but back to your question,yes it's effected me substanialy when i started(at 12 so i did smoke weed yet)and i could last 6-7 rounds but now 3 is a bitch but then ive also goten alot bigger and take shallow breaths(i usualy do meditation breathing all the time) so maybe it has something to do with oxygen deprevation because of that....but i dout it