If you were to die without realising it (peacefully in your sleep or something) then it wouldn't make a difference if you died in 50 years or tonight.
Everything is eternity. Time is just a man-made concept created to quantify eternity into terms we can understand and apply.
Think about it this way if you're concerned about "the nothing". Can you remember before you were born? Before you were conceived? The initial spark of "life"? ...You can't, right? Yet you don't feel at a loss for it... To me, this indicates we've always been here in some shape or form. Also, of course leading a full life matters - you may have children, you effect the world and those around you just by being part of it.