Michael Jackson is immortal now...
Imagine... You meay leave family and loved ones behind who do care. You might have been a good friend to someeone 10 years later if you had stayed alive and not wasted it on such activities. So when I say it is NOW that counts, I mean it is the NOW but with an eye to the consequences of your actions. This also means that if you decide to live your life like a jerk you will essentially have wasted your life. Yes, in that case you did make an impact but the impact was negative. People would generally be better off if you had never lived. Therefore you should make a point of making a positive contribution to everyone around you, make sure that when you die and cease to exist, people will notice and miss you. This missing and mourning is not a bad thing - that is just their way of honoring you and allow you in a sense to live on in a way after you are dead.
For example Julius Caesar - he has been dead for over 2000 years. Yet, every time you make an appointment and agree with someone to meet on a certain date. You can send a little "thank you" to Julius Caesar as it is due to him we have the calendar we have today. Sure, if he didn't do it, sooner or later someone else would have done it. However, he did it and so we honor him and in this sense he will have if not eternal life so at least live as long as we use that calendar - which is probably going to last for a long time still.
So one way to "live forever" is to make a name for yourself - be famous! However, in this case it does not so much matter if the impact is positive or negative. Adolph Hitler also "live forever" in this sense but most of us do not associate anything positive to his name. We generally think that life and history would have been better if he had never been born. So instead of honoring his name we curse his name. So, not only make a name for yourself, try also to make a postive name for yourself, do a positive contribution to society!
Even in the small. If you one day find you are elderly and you don't have much famliy who visit you any more and you don't have many friends who are left alive. Yet, every day you go to the park and feed the birds. The birds surely will appreciate that you are there and if you one day pass away and do not show up there, they will go hungry until some other old man and woman come and sit on that bench and feed them. Even this - albeit small - contribution to the world IS a contribution and is as such something that allow you in a sense to have what I would consider to be "eternal life" - that you make a postive impact on the world around so that when you are gone you will be missed.
This to me is then the meaning of life. Make sure you LIVE and that you make a POSITIVE CONTRIBUTION to the world around you. Do this and you will live forever.