Why did i get so tired what am i doing wrong?

It doesn't matter about your weight, it's about having energy. You need to have a decent sized meal prior to training, maybe something moderately high in carbs for the energy to do boxing training. This is why most people get tired, their body just doesn't have the fuel when it's required to work hard.

 

Experience.

 

Well then yeah I guess that is the problem. Maybe you go more tired this time since it was your first time sparring in a while and against a good opponent.

When the trainer says you feel asleep, maybe he didn't mean you were too relaxed, but just didn't throw enough.

 

It sounds like when I finished my college football career and was doing nothing but cardio. Sure I lost weight and thought I was in great shape but when I got home and went to the gym I gassed in a round. I hadn't been sprinting like I did when I was a player. I sure learned my lesson there.