Lack of Oxygen When Lifting

Hey everyone,

I have a problem that I need help with…

I am pretty new to weight lifting (3 months maybe), but I’ve been athletic all my life and particularly the past year. most of my exercise comes in the form of parkour (type it into youtube if you don’t know what it is) and most of those are bodyweight exercises.

I’m 6’0" and about 185 lbs. I eat very healthily.
now…my problem is that almost every time workout with weights my head starts to hurt like all the blood is rushing to my head and I have to yawn a lot. I realize this is an obvious lack of oxygen to the muscles and everywhere else.
Does anyone have any advice on what I can do to make that stop?
thanks.

Just make sure to breath every couple of reps, and dont wear a belt durring high rep squats or deadlifts.