Hey, you know, almoust every death is somehow painfull. But couple of minutes of pain is nothing comapred to cancer death for example. If you are scared of pain and fear a lot that probably you are not ready for know. For some people it's better to have some time to prepare theyselves. Also remember that every pain isn't eternal and there would be no "after". But the fail could be really painfull. So you should be engineer of your own end. Design it correctly! Deal with your emotions is a part of that design. Take your time, think, read. Death, i believe, could be not that scary.
Also i would love to tell you about my experience. Once me and my crazy girlfriend thought about how it feels to die. We strangled each other untill blackout. And u know that was preatty easy to lose consciousness. For me it was even a little euphoric.