How to deep throat?

I have gag reflex and every time I get it too deep my body acts funny and I feel like throwing up so I have to stop right away. How do I stop this shit? I even tried a deepthroat spray I bought for $13 but it doesn't work the way I thought it would. It numbs my throat for 2 mins and that's it. We've tried all kinds of different positions. I just want to be able to deep throat him cause I know he loves it.