Like the title suggests, if you could be immortal, your body would never age, you'd stay whatever age you are currently, would you? Really think about it before you answer...
Personally I wouldn't because even if you never die, your mind can only take so many memories...eventually you'd go insane and I'd rather be dead than a raving lunatic (x
edit to clarify the type of immortality we are discussing:
1) Your body would not age
2) Disease, poison, and venom won't harm you
3) Outside lethal forces (with the exception of those listed above --- e.g a bullet to the head) would kill you