Riddle that I cannot remember the answer to, Help!

[coloradosilver]

I was asked this riddle earlier today and I know that I’ve heard it before, but for the life of me I can’t seem to remember the answer. It goes like this:

You’re walking down a pathway when you come to two doors. Behind one door is certain death. Behind the other is eternal life and happiness. There are two guards standing in front of the doors. One of these guards always lies and the other always tells the truth. You cannot walk back the way you came, you must go through one of these doors. You may ask only one question to one of the guards before making your decision of which door to go through. What is the question you ask to ensure you choose the correct door (assuming you don’t want to die) to go through?

Any ideas? I know some of you have to of heard this before.