User blog comment:B214/Question and Answers 3/@comment-4547267-20140706235742/@comment-9339850-20140707020616

I wonder if him learning to stabilize his life force (being able to make it normal or fill himself with extra life force) could eventually become a power up; Something like, during a fight where he is exhausted, he is able to tap into the extra (probably infinite) force that he has sealed away when he's at a normal state.

This wouldnt make him overpowered per se; because if he isnt able to defeat the enemy, it doesn't matter how long he himself can fight.

And from what i keep reading.. everyone is confusing Life "Span" with Life "Force". Life Force can be seen as Life Span, but the same is not true reversed. Life Span is just time a person has can live for; Life Force is the energy needed to stay alive. Basically what im explaining is under normal conditions Issei's life span would end at the same time his life force wanes out (Span = Force). The second part of what i said can be seen as this: Because Issei's life force can drop to 0 (dead) at any point, it renders his life span meaningless (Force =/= Span)