Sounds to me like he's either waiting for death, or contemplating suicide. Death/Suicide would be the "shortest ending," as they happen quite quickly compared to one's lifespan (the "longest beginning").
The suicide angle, for me, comes from this part, where he implies that he's tired of life:
 It's taking everything to keep me from giving this
 All up for a chance to see the beginning and shortest ending
It also sounds like he may believe in reincarnation from this line:
 Well I'm starting the story again.
 Understanding the way this will end
Sounds to me like he's either waiting for death, or contemplating suicide. Death/Suicide would be the "shortest ending," as they happen quite quickly compared to one's lifespan (the "longest beginning").
The suicide angle, for me, comes from this part, where he implies that he's tired of life:  It's taking everything to keep me from giving this  All up for a chance to see the beginning and shortest ending
It also sounds like he may believe in reincarnation from this line: Â Well I'm starting the story again. Â Understanding the way this will end