Don't get married, don't have kids, don't grow old.
Be selfish, enjoy your life; the universe begins when you were born and the universe ends when you die.
The universe only exists when you are there to perceive it.
Live hard, live fast, experience everything ... and if you survive all that and are still alive at 60, then put in one last massive year and blow all your superannuation on sex, drugs, and every other pleasure ... and then order the euthanasia kit online and peacefully end your life.
The universe has existed for billions of years ... and this universe we live in is just one of billions of universes ... and this universe and many other universes will come and go for the next billions or maybe trillions of years. But as far as you are concerned that all only exists for the brief moment in time and space that your life exists ... so have fun ... indulge your carnal desires ... and when you are gone it's like you were never here ... the lamb you ate today, the cockroach you squashed, the weed you sprayed Roundup on ... all equally precious and all equally as insignificant as you ...
Enjoy! ...