Training His Breath Holding By Facesitting

Ive put on a big stopwatch on the computer screen - and ordered the slave to be my office chair. And Ill stop the time he can hold his breath! And Ill not make it easy for him - Ive put on a very hard jeans that will surely flatten his nose. I think a minute shouldnt be a problem... or will it be? Well, well see - but Ill make sure the loser suffers under my ass - hell be mercilessly smothered and feel my full weight on his face! He doesnt really help himself by struggling that much - he just wastes so much oxygen... he should just keep calm... guess Ill need to train him longer! And I really dont like to be disturbed by his moaning - so I put on headphones and start some music - then smother him again and the timer starts once again! Unfortunately, I can still feel him struggling... so I guess next time Ive to bind him so he cant move and then put on the headphones!