The purpose of our lives is to be happy. We live in hope, which means looking forward to something good. And there are increasing scientific findings that both our physical and mental well-being depend on our peace of mind.
There remain times when one can only endure. One lives on, one doesn't die, and the only thing that one can do, is to fill one's mind and time as far as possible with the concerns of other people. It doesn't bring immediate peace, but it brings the dawn nearer.
It is easy to remove the mind from harping on the lost illusion of immortality. The disciplined intellect fears nothing and craves no sugar-plum at the day's end, but is content to accept life and serve society as best it may. Personally I would not care for immortality in the least. There is nothing better than oblivion, since in oblivion there is no wish unfulfilled. We had it before we were born, yet did not complain. Shall we whine because we know it will return? It is Elysium enough for me, at any rate.
Meditation is like a single log of wood. Insight and investigation are one end of the log; calm and concentration are the other end. If you lift up the whole log, both sides come up at once. Which is concentration and which is insight? Just this mind.