In the past, the idea of immortaliy was mostly confined to religion, a reassurance that we would live on after our death in some other, spiritual sphere, so that we need not fear death but welcome it as an entrance to something different and glorious.
With the decline of traditional religion, that is no longer the case, yet the need to see ourselves as living on in some way after death, to leave a legacy, to be remembered, remains just as strong. In fact, it turns out that it's another of those human characteristics over which we have little control, it's part of our make up.
What I find disturbing is that some people are so obsessed with it that they forget to live their life now, sacrificing that to the creation of their magnum opus (or whatever!). I'm sure you know somebody like it - so focused on the future, so desperate to make a difference and be recognised for their efforts, so absorbed and involved in their work for the benefit of future generations, that their own, and their family's, life passes by unnoticed. In fact, they may well be missing what is right in front of their noses, oblivious to their true legacy.
So, next time you feel you've not done anything worthy of acclaim, reconsider. It could be that your ambitions are too lofty or it could be that you already have much to be proud of - those little kindnesses add up. And if that doesn't help and you're still not sure how you feel about the whole subject, ask yourself - would you rather be living a full and happy life now, or have lots of people at your funeral?